The answer is B. 14(m − 8)
m represent the weight of the boxes that Marco lifted.
d represent the weight of the boxes that Drew lifted.
The boxes that Drew lifted each weighed 8 lb less than the boxes Marco lifted:
d = m - 8
So the weight of one box that Drew lifted is (m - 8). Since he lifted boxes, the total number of pounds Drew lifted is 14(m - 8)