Answer:
x = 12
length = 4 cm
width = 20 cm
Step-by-step explanation:
a = lw
Plug in the givens
80 = (x - 8)(x + 8)
Multiply
80 = x^2 - 64
Add 64 to both sides
144 = x^2
Take the square root of both sides
x = ±12
(The negative root is extraneous since the dimensions can not be negative)
x = 12
length = x - 8 = 4 cm
width = x + 8 = 20 cm
