What is the percent of change in the area?

Question

Two of the opposite sides of a square are increased by 20% and the other two sides are decreased by 25%. What is the percent of change in the area?

Answer 1

Original sides all measure x

 

New rectangular area has adjacent sides 1.2x (note 20% increase) and 0.75x (note 25%) increase.

 

New rectangular area = 1.2(0.75)x² = 0.9x²  so this is a ten % change (reduction) of original area.

 

This answer can be written as -10%