A notebook has a perimeter of 36 inches and an area of 80 square inches. What are the dimensions of the notebook?

Let L be length and W be width

The perimeter of a rectangle is 2W+2L=36

Thus 2W=36-2L, W=18-L

Area of a rectangle is WL=80

Thus (18-L) (L) = 80

18L-L^2=80

L^2-18L+80=0

(L-8) (L-10)

Thus L can either be 8 or 10.

Because WL=80

If L is 8, then W=10

If L is 10, then W=8

So either way, the notebook is 8 by 10