Question

1. The number a is 4/5 of the number b. What part of number a is number b?
2. The number a is 1/5 smaller than the number b. By how much is b bigger than a?

Answer 1

Writing some equations out might help!

1) You know that a is 4/5 of b. This can be written as:$a = \frac{4}{5} b$.
To find what b is equal to, multiply both sides by 5/4: $\frac{5}{4}a = b$.
A is 5/4 B. 

2) You know that a is 1/5 smaller than b. This can be written as: $a = b - \frac{1}{5}$.
To find b, just add 1/5 to both sides: $a + \frac{1}{5} = b$.
B is 1/5 bigger than a.