Answer:
length of base is 10
Explanation:
The area of the entire firgure is 1600 cm^2. There are 4 equal sized pennants, so each pennant is 1600/4 = 400
the bottom pennant has area 400 and is triangular shaped. the area of a triangle is 1/2 b h.
A = 1/2 b h given height is 80 and area is 400. plug these values in
400 = 1/2 b (80)
400 = 40 b divide both sides by 40
b = 10