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
