A rectangle poster covers an area of 380.16 square inches of a display board. The width of the poster is 12 inches less than its length. Find the width of the poster.

Let the width = x - 12

the length = x

we have this area equation: x (x-12) = 380.16

=>x^2-12x-380.16=0

=> (5x-132) (5x+72) = 0

=>x = 132/5 and x = - 72/5 (no)

=>The width of the poster is: 132/5 - 12 = 72/5 inches