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

Answer 1

Let's say the store sold c cakes and p pies.
We know that cakes cost 5*c and pies cost 7*p.
We also know that the store sold 15 baked goods, so c + p = 15.
The total amount of money earned is $91, or 5*c + 7*p = $91.
Let's solve this system of equations. Multiply the first equation by 5 and subtract it from the second equation: 5*c + 7*p - 5*c - 5*p = $91 - $75.
This simplifies to 2*p = $16, so p = $16 / 2 = <<16/2=8>>8.
Since c + p = 15, then c = 15 - 8 = <<15-8=7>>7. Answer: \boxed{7}.