Question

A bakery sold 120 cakes and pastries for a total of $1,600. If a cake costs $20 and a pastry costs $10, how many cakes were sold?​

Answer 1

Let c= cakes and p=pastries then create the following equations

c + p = 120
20c + 10p = 1600

Use the first equation and solve for p and then substitute into second equation and solve for c

p = 120 - c

20c + 10(120 - c) = 1600
20c + 1200 - 10c = 1600
10c = 400
c = 40

40 cakes were sold