A photo 5 inches wide and 8 inches long is enlarged.

How wide is the new photo if it is (1) 12 inches; (2) 20 inches; (3) 10 inches long?

1. 7.5 inches

2. 12.5 inches

3. 6.25 inches

1. Let original dimensions be W1 and L1

New dimensions designated as W2 and L2

Equation: W2/W1=L2/L1 ... A equal proportion

Thus ...

(1) W2/5=12/8. (2) W2/5=20/8

W2 = 5 (12/8) W2=5 (20/8)

W2=5 (1.5) W2=5 (2.5)

W2=7.5" W2=12.5"

(3) W2/5=10/8

W2=5 (10/8)

W2=5 (1.25)

W2=6.25"