After a 12% rise in membership, a library now has 1,344 members. How many new members did it gain?

Explanation

1. 01

   $1{,}344 = 112\%$ of the old membership.

2. 02

   Old membership = $\frac{1344}{1.12} = 1{,}200$.

3. 03

   New members = $1{,}344 - 1{,}200 = 144$.