Question

What is the percent of increase for 20 to 36?

Answer 1

from 20 to 36 is  a difference of 16.

now, if we take 20 to be the 100%, what is 16 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 20&100\\ 16&x \end{array}\implies \cfrac{20}{16}=\cfrac{100}{x}\implies 20x=1600 \\\\\\ x=\cfrac{1600}{20}\implies x=80$

Answer 2

(new -original)/original * 100

(36-20)/20 * 100

16/20 * 100

.8*100

80

80% increase