<PRE><B>Question 446623</B>
Area = Length * Width
A = L * W
A = 100 sq. ft
W = ?
L = W + 15
Substituting
100 = (W+15)*W
100 = W^2+15W
Subtract 100 from both sides
0 = W^2 + 15W -100
Factor
What are the relevant factors of 100, one positive and one negative that when added equal 15?
5 * 20 = 100
20 -5 = 15
OK
(W-5)(W+20) = 0
So,
W = 5
W = -20
But
We cannot have negative width, so our only applicable solution is
W = 5
Looking back, we see that
L = W + 15
L = 5 + 15
L = 20
Answer:
The banner will have length of 20 and width of 5.
Done.</PRE>