Question

120 books increased by 10%

Answer 1

10% means 10 out of 100.

So 10% of 120= $\frac{10}{100}*120= \frac{1}{10}*120=12$

So total number of books now = 120+12 = 132

Answer 2

P% = $\frac{p}{100}$ ⇒ $\frac{10}{100}= \frac{10\div10}{100\div10} = \frac{1}{10}$

$\frac{1}{10}*120 = \frac{120}{10} =12$ ⇒ $120 +12 = \boxed {132}$ books