What is the area of the box?
B * H = A
54 in² * 13 in = A
702 in³ = A
The area of the box is 702 in³
Does he have enough sand?
If not, how many more bags does he need?
I am not sure how many bags he does have, so I cannot answer these two questions. I can, however, tell you how many bags he will need.
702 in³ / 36 in³ = 19.5 bags
He most likely will not have half a bag, so he will need 20 bags in total.
