Question

Renee has a total of 12 cookies in chocolate chip and peanut butter, C + P = 12. The number of chocolate chip cookies is three times the number of peanut butter cookies, C = 3P. How many of each type of cookie does she have?

Answer 1

Set up a system of equations in 2 variables.

Answer 2

Renee has 9 Chocolate chip cookies and 3 peanut butter cookies.

Explanation:

This is a system of equations:

C + p = 12

C = 3P

All you need to do is substitute C for 3P in the first equation.

C + P = 12

3P + P = 12

4P = 12

Divide both sides by 4

4P/4 = 12/4

P = 12/4

P = 3

Now, substitute P for 3 in the first equation.

C + P = 12

C + 3 = 12

Subtract 3 from both sides

C + 3 - 3 = 12 - 3

C = 12 - 3

C = 9

C = 9, P = 3