Answer: (5/4- 1) X 100% = 25%, (4/5- 1) X 100% =-20%, 5x (1+40)

2。 The quantity of A is more than that of B 10%, and the ratio of B to A is (10: 1 1).

Answer: If the number of A is more than the number of B 10%, then the number of A = 1. 1, and the ratio of B to A is 1: 1 0:160.

3。 Answer: 1/0.8= 1.25, then the number of girls is (125)% of that of boys.

4。 The number of A is twice that of B, and A is more than B (100)%. ..

Answer: A number =2 B number, and A number is greater than B number (2- 1) x% = 100%.

5。 Answer: The salt content of a brine is 10%, that is, the salt content in brine is 1x 10% = 10%, and the water volume is1-kloc-0/0% = 90%.

6。 Answer: The number B is 87.5% of the number A, that is, the number B =0.875 and the number A: the number B = 1: 0.875. If the number b is 56, then the number A =56/0.875=64.

7。 40% of A = 50% of B, A =5/4 B, A = 120, B = 120/5X4=96.

8。 9。 10 problem can be calculated according to the above method. Take the base number as 1, calculate other numbers according to the base number, and then compare with the base number to calculate the correct answer.