Answer:
2784 cm^2
Step-by-step explanation:
I have indicated in the pic there are 4 types of rectangles:
green : 20 x 4 = 80
red : 18 x 4 = 72
yellow : 20 x 18 = 360
blue : 18 x 16 = 288
green has 6 identical surface area so 6 x 80 = 480
red has 4 so 4 x 72 = 288
yellow has 4 so 4 x 360 = 1440
blue has 2 so 2 x 288 = 576
total : 480 + 288 + 1440 + 576 = 2784
