width of shaded part:
6^2+2^2=w^2
36+4=w^2
40=w^2
w= sqare root 40
w= 6.32455532
length of shaded part:
12^2+4^2=l^2
144+16=l^2
160=l^2
l=square root of 160
l=12.6491106407
area=12.6491106407*6.32455532
=79.9999999959which is 80, because those decimals are endless, if you multiply 12.6491106407*6.32455532, answer wouldn't be accurate, so you should round up to 80. If you use another way to solve the q, which is calculate the bigger rectangle and then subtract the area of the triangles, you will get 80 as your answer.