Question

By decreasing each dimension by 2 units, the area of a rectangle decreased from 40 square feet (on the left) to 16 square feet (on the right). Find the percent decrease in area​

Answer 1

60%

Explanation:

40 ft² is 100%

so, 1% = 0.40 ft²

now we need to ask, how often did 1% fit into the 16 ft².

that means

16 / 0.4 = 16 / (4/10) = (16×10)/4 = 160/4 = 40 %

so, the new, smaller area is only 40% of the original area.

and that means, that the area decreased by 100-40 = 60%