Question

You and your sister are selling cookies to help raise money for your field trip. You start out with $24 and sells each bag of cookies, c, for $3. Your sister doesn’t start out with any money but sells her bags of cookies for $5 each. How many bags of cookies must they sell in order for them to raise the same amount of money?

Answer 1

12 bags of cookies.

Explanation:

Since you already start out with $24, you will have a y-intercept of 24. Your slope will be 3, since each bag sells for $3.

Your equation will be y = 3c + 24.

Your sister does not start out with money, so she will have a y-intercept of 0. Her slope will be 5, as each bag sells for $5.

Her equation will be y = 5c.

Since y = y, you can set the two equations equal to each other.

3c + 24 = 5c

5c = 3c + 24

Subtract 3c from both sides

2c = 24

Divide both sides by 2

c = 12

So, they must sell 12 bags of cookies to raise the same amount of money, $60. Yum!

Hope this helps!