Question

by decreasing each dimension by 1 unit, the area of a rectangle decreased from 30 square feet (on the left) to 18 square feet (on the right). find the percent decrease in area. the percent decrease in area is (%).

Explanation:

Step1: Recall percent - decrease formula

Percent decrease = $\frac{\text{Original value}-\text{New value}}{\text{Original value}}\times100\%$

Step2: Identify original and new values

The original area of the rectangle is $A_{1}=30$ square feet and the new area is $A_{2} = 18$ square feet.

Step3: Substitute values into formula

Percent decrease=$\frac{30 - 18}{30}\times100\%=\frac{12}{30}\times100\%$

Step4: Calculate the result

$\frac{12}{30}\times100\% = 0.4\times100\%=40\%$

Answer:

$40$