Concept:The change is the amount paid minus the total cost of the socks.Explanation:Cost of one pair of socks is GH₵17.50.Cost of 3 pairs =3×17.50=GH₵52.50.The boy paid with two GH₵50.00 notes, so total payment =2×50=GH₵100.00.Change received =100.00−52.50=GH₵47.50.Answer:C. GH₵47.50