A.
5 * 2 = 10
8 * 2 = 16
10 cm by 16 cm is the new dimensions. Area = 160 sq cm. Perimeter = 52 cm.
B.
5 * 3 = 15
8 * 3 = 24
15 cm by 24 cm is the new dimensions. Area = 360 sq cm. Perimeter = 78 cm.
C.
The areas for the different sized photos both still maintain a ratio of 5:8 cm.