Answer:
x = 5
Explanation:
Area of rectangle = 12x8= 96 in^2
shaded portion =78 in^2
Using these two areas and subtracting we know that the area of the unshaded triangle is 18 in^2
Area of unshaded portion algebraically = (12 x (8-x))/2
now if we set these two equal to each other we will be able to find x.
48-6x = 18
30 = 6x
5 = x