Question

A photo is 12in wide by 18in. tall.If the width is scaled down to 9 inches how tall should the similar photo be?

Answer 1

width1 / height1 = width2 / height2 
12 / 18 = 9 / x

Cross multiply
12x = 18 * 9 = 162
Divide both sides by 12
x = 13.5

The similar photo should be 13.5 inches tall.

Answer 2

Let x be the new length.

12/9=18/x
⇒ x=18*9/12= 13.5

The new length should be 13.5 in long.

Hope this is helpful~