Question

The length of a rectangular garden is 5 feet greater than the width. the are of the rectangle is 300 square feet. find the length and the width.

Answer 1

Set up a system of equations to solve the question. 
w=width, l=length
w+5=l
w*l=300
Plug (w+5) in for l in the second equation.
w*(w+5)=300
Distribute
w^2+5w=300
w^2+5w-300=0
(w+20)(w-15)=0
w=-20,w=15