Answer:
3 1/4 pounds
Step-by-step explanation:
Marco starts with 8 1/2 pounds, to make things easier rewrite it as 8.5.
He uses 1/4 (or .25) of the apples. 8.5 * .25 = 2.125. Subtract this 2.125 from the 8.5 since it's what's being used. 8.5 - 2.125 = 6.375
Then he uses 3 1/8 (or 3.125) pounds. Subtract 3.125 from the 6.375 we got previously to get 3.25.
Marco has 3.25 pounds left which can be rewritten as 3 1/4 pounds.