One: 1 class has 50 students, class 2 is one fifth more than class/kloc-0, and class 2 has (60) students. There are 50 people in Class Three, which is a quarter more than Class Four, and there are (40) people in Class Four.

Two: The sum of number A and number B is 28, number A is three-quarters of number B, number A is (12), and number B is (16).

Three: 225 ÷ (1+1/5-3/4) = 500 yuan.

Do you have the wrong number?

Five: suppose the original plan was to build an x meter.

x( 1+ 1/4)= 1200

X=960 meters.

960 * 2 =1920m

A: The original plan was 1920m.

Remember to add points