Answer:
200 sq cm
Step-by-step explanation:
Lateral surface area is the surface area without the bases, or without the top and bottom. So, you just add up the area of the 4 sides.
The front and back are both 10 x 20, so 200 each = 400
The left and right are 5 x 20, so 100 each = 200
The lateral surface area is 200 sq. cm.
