Question 450566
"If a rectangle's length is increased by 30% and its width is decreased by 30%, what is the percent change in area?" 
.
Let x = original width
and y = original length
then
area = xy
.
after change:
width = x - .30x = .70x
length = y + .30y = 1.30y
then
area = (.70x)(1.30y) = .91xy
.
percent change in area:
(xy - .91xy)/xy *100
(.09xy)/xy *100
.09 * 100
9% decrease in area