Answer:
20 cm
Step-by-step explanation:
Find the area of the square first ( b x h ) then the area of one of the triangles (1/2 b x h). The sqaures base is 3 and height is 4 so the area is 12 ( 3 x 4 = 12) and the triangles you multiply the base x height again, and divide it in half
( 2 x 4 1/2). This leaves you with twenty.
