A corner store sells two kinds of bakersd goods: cakes and pies. A cake cost 5$ and a pie cost 7$. In one day, the store sells 15 baked goods for a total of 91$. How many cakes did they sell?

Question

A corner store sells two kinds of baked  goods: cakes and pies. A cake cost 5$ and a pie cost 7$. In one day, the store sells 15 baked goods for a total of 91$. How many cakes did they sell?

Answer 1

Let C=number of cakes and P=number of pies. P+C=15 so P=15-C.

5C+7P=91 (sales)

Substitute for P: 5C+7(15-C)=5C+105-7C=91, 105-91=14=2C, so C=7 and P=8.

So 7 cakes (and 8 pies) were sold.