Question 224248
the length of a rectangle is increased by 120% and its width is decreased by 20%, what is the resulting percentage increase or decrease in the area? Justify your answer algebraically.


Area of a rectangle = LW


If area is increased by 120%, then its new length is: 220% * L = 2.2L


Since its width is decreased by 20%, then its new width is: 80% * W = .8W


This makes its new area: 2.2L * .8W = 1.76LW


The difference in the original and new area is an increase of: 1.76 - 1, or .76 


Therefore, the increase in its area is: {{{(.76/1) * 100}}} = {{{highlight_green(76)}}}%