need help solving word problem

Question

define variables, write an equation, and then use the equation in the solving process.
 
The length of a rectangular frame is 3 cm more than the width. The area inside the frame is 70 square cm. Find the width of the frame.

Answer 1

Let w = width; let l = length; let A = area

 

l = w + 3

 

A = l x w;  A = (w + 3) x w = 70

 

 w^2 + 3w = 70

 

 w^2 + 3w - 70 = 0

 

0 = (w + 10)(w - 7)

 

w = 10, which is not possible

 

w = 7