Answer:
16cm
Step-by-step explanation:
The area of a 2d figure is w x h. We know the area, a, is 80cm^2, the height, h, is 5, and the width, w, is 2x + 8.
Since we are solving for x, we want to isolate the variable.
5 x 2x + 8 = 80
80/5 = 2x + 8
We can now solve for x.
80/5 = 2x + 8
16 = 2x + 8
16 - 8 = 2x + 8 - 8
8 = 2x
8/2 = 2x/2
4 = x
We aren't done, we still need to solve for w, where we now know x = 4
w = 2x + 8
w = 2(4) + 8
w = 8 + 8
w = 16
