Hey!
We could rewrite the problem as:

Since we have a negative number, we could rewrite the fraction like this.

Let's simplify it...

Our answer would be:

Thanks!
-TetraFish
Hey
Width of the photo = 3"
Length of the photo = 5"
New length of the photo = 7 inches
Then
3/5 = x/7
5x = 7 * 3
5x = 21
x = 21/5
= 4.20 inches
Hoped I Helped