First question
The rectangle is 136 cm long and 80 cm wide. To cut out more and bigger squares, of course, it is to calculate the greatest common divisor.
Length136 =100+36 = 4x (25+9) = 4x34 = 8x17;
Width 80 = 8x10; ;
The cut square is 8 cm long;
Total * * * can cut out 17X 10= 170.
the second question
16 minutes, 40 minutes and 25 seconds, 17: 00 to return. Let's first calculate how long Zhai Zhigang stayed outside the cabin.
17: 00-16: 40: 25 = 0: 19: 35,19: 35;
In fact, less than 20 minutes, 25 seconds shorter, that is, 20x60-25 =1200-25 =1175 seconds;
7.8 km/s speed times time.
7.8x 1 175 = 39x 235 = 235 x40-235 = 9400-235 = 9 165km。
Third question
Lingling goes every two days, and Lili goes every three days. In other words, Lingling goes once every three days, and Lili goes once every four days.
Just as we go together in July 10, Lingling's next time is July 13, and Lili's next time is July14;
Let me see, 10 days, 1 1 day, 12 days, 13 days, 14 days, 10 days and 13 days, the difference is different.
Calculate the least common multiple, 3X4=4X3= 12, we can calculate 12 days, and two people walk together once;
Let's take another look. There are 3 1 day in July and August. How many days does the holiday end from July 10 to August 3 1?
3 1+3 1- 10 = 52 = 48+4 = 12x 4+4。 After July 10, the two of them went together for four times, and this time on July 10, they were * *.
The fourth question
Xiaoming 12 years old is a dragon, and grandpa is a snake. In the zodiac, the snake follows the dragon closely, but it is impossible for grandpa to add the zodiac round by round when he is 1 1 year old and his grandson is one year old, which also provides a basis for our continued analysis.
After all, the age difference between the two generations can't be 12 years old, and it can be counted several times less.
1 1+24=35, impossible, dad is 35 years old, 23 years older than his son;
35+24=59, so it is possible that grandpa is 59, 47 years older than his grandson;
59+ 12=7 1, so it is also possible that grandpa is 7 1, 59 years older than grandson;
7 1+ 12=83, which is impossible again. Grandpa is 7 1 year older than his grandson, so it's too late for grandpa to have no father.
There is more than one answer to this question. Grandpa may be 59, or 7 1 year old.
The fifth question
Let's have a look. Car A leaves from City A and returns at the original speed after 30 minutes. The city was delayed for 30 minutes, and then hit the road again at the original speed. You know, walk for 30 minutes, return for 30 minutes, and delay for another half an hour. From starting together to getting back on the road, a car was an hour and a half late;
Let the distance between the two cities be X. According to the equation, car A travels 45 kilometers per hour and car B travels 40 kilometers per hour.
x/40 + 0.5 = x/45 + 1.5
9x/360 = 8x/360 + 1
Multiply both sides by 360 and remove the denominator.
9x = 8x + 360
x = 360
So the distance between the two cities is 360 kilometers.
The sixth question
The equation is to find the equivalence relation. Regarding age, the age difference between people is always the same.
Let my brother's age be x this year and his age be x/2 this year;
Three years later, the elder brother's age became x+3 and the younger brother's age became x/2 +3. Let's make an equation.
(x+3)X 3/5 = x/2 +3
Multiply both sides of the equation by 10, and remove the denominator.
(x+3)X 6 = 5x +30
6x + 18 = 5x +30
x = 12
It turns out that my brother is 12 years old this year.
Question 7
Teddy bears are purchased in 2.8 yuan and sold in 3.6 yuan. When it sold 5/6 of the total amount, it not only recovered all the costs, but also made a profit in 24 yuan.
Let's set a teddy bear to buy X and make an equation.
(3.6 times) X5/6 = 2.8 times +24
3x = 2.8x + 24
0.2x = 24
x = 120
A total of 120 teddy bears were purchased. This last question is also the simplest equation.