Well, let's look at the answer choices.
A) If you want to fond the total cost of two sweaters you would add, not divide. So this isn't it.
B) To find out how much older someone is you would subtract. So this isn't it either.
C) To find out how many desks are needed you would multiply, since you know you need 3 rows of desks with 7 students each (3 x 7). Again, not it.
D) To find out how many pencils each student would get, you'd divide. You would divide 56 by 9. So your answer is D.
