Explanation:

There are two methods you can use:

$1$. Find the 20% of $30 and add it on. 20% " of "$30

$= \frac{20}{100} \times \frac{30}{1}$

=$6 The new price is $30+$6 =$36

$2$. Add 20% onto 100% and find 120% of $30 If 20% is added on the the new price represents 120% 120% " of "$30

$\frac{120}{100} \times \frac{30}{1}$

=\$36#

The second method is more direct and can also be used easily in algebra because it involves multiplication.