Question

A carpenter draws a plan for the top of a table he is building. The width of the table top is 20 inches and the length is double the width. He wants to know how the area of the table top will be affected if the length is increased by x inches.

Answer 1

W = 20 
l = 2w = 40 
if l is increased by x, w is increased by 1/2x 
A = l x w = (40 + x)(20 + 1/2x) = 1/2(40 + x)(40 + x) 
A = (40+x)²/2