Explanation:
if the new photo is 12 inches long than the photo is enlarged
12/8=3/2
so the new photo is (3/2)*5 =15/2=7.5 inches wide.
Now,about the new photo 20 inches long it means that is enlarged 20/8=5/2 inches
so the new photo is wide 5*(5/2)=25/2=12,5 inches.
The photo 10 inches long is enlarged 10/8=5/4 inches.So the new photo is 5*(5/4)=25/4=6,25 inches wide.