To find the money he would have to spend on 5 bags of cat food, we would first need to find the cost of a single bag of cat food by dividing $15.75 by 3:
15.75÷3
=$5.25
Afterwards we can mutiply the above answer by 5 to find the answer:
5.25×5
=$26.25
Therefore the answe is $26.25.
Hope it helps!