For this question, first find the area of the original square.
30*30 = 900.
Next, find the length of the sides if it is increased by 20%.
30 = 100%.
3 = 10%
6 = 20%.
So, the new length would be 36 cm. Next, find the new area.
36 * 36 = 1296.
The original area was 900.
1296 - 900 = 396
(396/900) *100 = 44%
44% increase.
Hope this helps!