For the next RSM Award ceremony, it was decided to decrease the length of the main poster by 12% and to increase its width by 15%. By how many percent did the poster's area change? Did it increase or decrease?

Let the original area = WL

If the width increased by 15% then the new width =1.15 W

If the length decreased by 12% its new width = (1 -.12)L = .88L

So....the new area =

1.15 W * .88 L = 1.012 WL

Its area increased by 1.012 - 1 = .012 = 1.2 %