If a new paint is set as A yuan per kilogram, then A paint a+3 yuan, B paint a- 1 yuan/kilogram.
100/(a+3)+240/(a- 1)=( 100+240)/a
10(a- 1)a+24(a+3)a = 34(a- 1)(a+3)
5a？ -5a+ 12a？ +36a= 17a？ +34a-5 1
3a=5 1
A= 17 yuan
New coating per kilogram 17 yuan.
33. A, B and C ran the 60-meter race. When Party A reaches the finish line, it is 10 meters ahead of Party B and 20 meters ahead of Party C. At the original speed, how many meters ahead of Party C will Party B reach the finish line?
Solution: A run 100m, B run 90m and C run 80m.
Set B to the finish line and C to run one meter.
therefore
90:80= 100:a
90a=8000
a=800/9
Leading C 100-800/9= 100/9 meters.
34. The bus and truck leave from A and B at the same time and meet in four hours. As we all know, the speed ratio of bus to truck is 7: 5. How many hours will it take after the truck arrives at the meeting?
Solution: Let the truck arrive at location A within one hour.
5/ 12:4=7/ 12:a
5/ 12a=7/ 12×4
A=28/5 hours
35. There are several red and white balls. The ratio of red ball to white ball is 5: 7. Later, six red balls were released. The ratio at this time is 1: 1. How many balls are there now?
Solution: There are 5a red balls and 7a white balls.
According to the meaning of the question
(5a+6):7a= 1: 1
7a=5a+6
2a=6
a=3
Now there is (5+7)×3+6=42.
36. There are 85 students in Class A and Class B, and Class B 1 1 is transferred to Class A, and the ratio of Class A to Class B is 9: 8. How many people are there in Class A?
Solution: There are A people in Class A, so there are 85-a people in Class B..
[a+(85-a)× 1/ 1 1]:(85-a)×( 1- 1/ 1 1)= 9:8
8a+8/ 1 1×(85-a)= 90/ 1 1×(85-a)
88a+680-8a=7650-90a
170a=6970
a=4 1
There are 4 1 person in class a.
37. Class A donated two-thirds of the sum of Class B and Class C, and Class B donated two-fifths of the sum of Class A and Class C. If Class A and Class B donated 144 yuan, how much did Class C donate?
Solution: class a donation a, class b donation144-a.
Class c donation (144-a)/(2/5)-a=360-7/2a.
According to the meaning of the question
a=( 144-a+360-7/2a)×2/3
3a=288-2a+720-7a
12a= 1008
A=84 yuan.
Then Class C donated 360-7/2×84=66 yuan.
38. The simplest fractional sums of two identical molecules are 1 and 18, and the ratio of the two denominators is 2: 3. What are the two scores?
Solution: Let denominators be 2a and 3a respectively.
therefore
1/(2a)+ 1/(3a)= 25/ 18
5/(6a)=25/ 18
a=3/5
Then these two scores are 5/6 and 5/9 respectively.
39. There is a bus with a body length of 12 meters in the street, which runs from east to west at a speed of 18 kilometers per hour. On the sidewalk, two people ran towards each other. At some point, the bus caught up with A and left A six seconds later. After 90 seconds, the car met Run B, which took 1.5 seconds. The bus left B. How many seconds before A and B meet?
Solution:18 km/h = 5 m/s.
Car and A are catching up, with speed difference =12/6 = 2m/s.
The speed of A is 5-2 = 3m/s.
When the car meets B, the speed sum is =12/1.5 = 8m/s.
The speed of B is 8-5 = 3m/s.
Let the distance between Party A and Party B be s meters.
When the car meets B, the a * * line s-5×6-3×6=s-48.
According to the meaning of the question
(5+3)×90=s-48
s-48=720
S = 768m.
After the car leaves Party B, the distance between Party A and Party B is 768-(3+3) × (6+90+1.5) =183m.
Then meet again after 183/(3+3)=30.5 seconds.
87. The distance between A and B is 36 kilometers. Party A and Party C set out from Party A and Party B at the same time, with opposite directions. Party A travels 7 kilometers per hour, Party B travels 5.5 kilometers per hour and Party C travels 3.5 kilometers per hour. How many hours does Party A leave at the midpoint between Party B and Party C?
Solution: Suppose it takes an hour.
7a-5.5a=36-7a-3.5a
12a=36
A=3 hours
88. Both Party A and Party B set out from East and West towns at the same time. Party A travels 6 kilometers per hour and Party B travels 5.2 kilometers per hour. They met at a distance of 1.2 km from the midpoint of the two towns. How many kilometers away are the two towns?
A travels 6-5.2=0.8 km/h more than B.
When meeting, * * * walk 1.2×2=2.4 km.
Meeting time =2.4/0.8=3 hours.
Then the distance between the two places = (6+5.2) × 3 = 33.6km.
89. Two ships, A and B, left the docks of the east and west ports at the same time, and met in six hours. The hourly distance ratio between the two ships is 2: 3. After the two ships meet, B will continue to sail. How many hours does it take to get to Donggang Wharf?
Solution: The speed ratio of Party A and Party B = inverse time ratio = 3: 2.
B takes 2/3 as long as A.
Then it takes 6×2/3=4 hours for B to reach the dock of the frozen port.
90. The fast train and the slow train travel in opposite directions from A and B respectively. After meeting, they moved on. When the distance between two trains is 2 10 km, the express train will travel 3/4 of the whole journey and the local train 3/5 of the whole journey. How many kilometers is it between A and B?
Solution: The distance between Party A and Party B = 3/5-(1-3/4) = 3/5-1/4 = 7/20.
Distance between Party A and Party B = 2 10/(7/20) = 600km.
9 1. It takes five hours for the bus to travel from Station A to bilibili, and seven hours for the truck to travel from bilibili to Station A. Two cars leave from two stations at the same time, and the truck stops for two hours. When they met, how many more miles did the bus walk than the truck?
Solution: Bus speed = 1/5, truck speed = 1/7.
The truck stops for 2 hours.
Then, if the bus travels for 2 hours, it is the whole journey 1/5×2=2/5.
The whole journey of two cars 1-2/5=3/5.
Distance ratio of bus and truck = speed ratio = inverse ratio of time = 7: 5.
Then as soon as they met, the bus * * * made 2/5+3/5× 7/12 = 2/5+21/60 = 3/4.
The truck has moved 1-3/4= 1/4.
Then there are 3/4 more buses than trucks-1/4 =1/2.
92. If the speed of the car from A to B is 5 kilometers slower than the scheduled hour, the arrival time will be longer than the scheduled time 1/8, and if the speed is increased 1/3, the arrival time will be earlier than the scheduled time 1 hour. Find the distance between a and b?
Solution: See 1 unit of original time.
If the speed is 5 kilometers per hour,/kloc-0 /× (1+1/8) = 9/8.
The ratio of original speed to actual speed is 9/8: 1.
Then the actual speed is 9/8- 1= 1/8 slower than the original speed.
Then the actual speed =5/( 1/8)=40 km/h.
Original speed = 40+5 = 45 km/h.
When the speed increases 1/3, the ratio of the actual speed to the original speed is (1+1/3):1= 4/3:1.
The time ratio is 1: 4/3.
The actual use time is 4/3- 1= 1/3.
So the actual time is 1/( 1/3)=3 hours.
The original time was 3+ 1=4 hours.
AB distance = 45× 4 = 180km.