A:12-2/7 = (84-2)/7 = 82/7 =115/7,
2. It takes four fifths of the total length to build an expressway in four days, accounting for 1/5 of the total length every day on average. It will take (5) days to complete this highway.
Answer: (4/5)/4 =1/51/(1/5) = 5 (days)
3.Obana Xiaojun went to buy a picture, and Xiaojun bought 2.5 times that of Xiaohua. Xiaohua bought another 30, and now the number is equal. How many tickets did you buy? (Equation solving).
Answer: If Xiaohua buys X, Xiaojun buys = 2.5x..
So X+30=2.5X 1.5X=30, so Xiaohua buys X=30/ 1.5=20 Xiaojun buys =2.5X=2.5*20=50.
In the class on June 4th, there were only five more boys than girls by a quarter. How many girls are there in Class 64?
A: There are many boys 1/4 boys =5, so boys =2*5=20 (people) girls =20*3/4= 15 (people).
5. Build a cement road with a width of 3.6m and a thickness of 0.2m.. If you mix 72 cubic meters of concrete, how many meters can you spread?
Answer: Pavable x meter = 72/(3.6 * 0.2) = 72/0.72 =100 (meter).
6. The area of a square is 18 square centimeter, and the shaded part is one ninth and one twelfth of the square. What is the area of a rectangle?
A: The topic should be "The area of a square is 18 square centimeter, and the shaded part is one ninth of the square and one twelfth of the long (regular) square. How many square centimeters is the area of a rectangle? "
So the area of the rectangle = 18/9* 12=24 cm2, and the shadow area =2 cm2.
7. Saw a rectangular piece of wood with a length of 24cm into four sections, and the surface area increased by 48cm2 compared with the raw material. What is the original volume of this piece of wood in square centimeters?
A: If the small cross section is X, the surface area is 6X=48 X=8 higher than that of the raw material.
So the original volume =8*24= 192 cm2.
8, rectangular container, the bottom is a square with a side length of 40 cm. A rectangular iron block with a height of 100 cm and a bottom length of 10 cm stands upright in the container, which is 50 cm deep. Now gently lift the iron block up 30 cm. So, how long has the part of the iron block exposed to the water been soaked in water?
Answer: Lift volume =30 cm * 100 cm2 =3000 cm3.
Water level difference = 3000/40 * 40 =1.875cm.
Now the water depth is 50-1.875 = 48.125cm.
So the length of the part soaked in water = current water depth-lifting height = 48.125-30 =18.125cm.