x = width
x + 10 = length
x * (x+10) = 75
x² + 10x = 75
- 75 -75
x² + 10x -75 = 0
(x - 5)(x + 15) = 0 Factor
Either x-5 = 0 or x+15 = 0
Solve for x:
x-5 = 0
x = 5
x+15 = 0
x = -15
Since a rectangle's dimension can't be negative, x will equal 5. x+10 = 15.
Your final answer should be 5 in. by 15 in. Hope this helps!