You have to work out the area of each side. The two identical triangles are 6x4=24 because 8/2 is 4. The base is 8x5=40. The back is 6x5=30 and the top is 10x5=50. You then add them all together to get 144 ft squared.
The answer is A) -4/25 because when you multiply 8/15 and -3/10, you can simplify the expression to 4/5 times -1/5, which equals -4/25.