kristin and rob are selling pies for a school fundraiser. customers can buy blueberry cookies and blackberry cookies in boxes of 12. they sold blueberry cookies $9 a box and blackberry cookies for $12 a box. they earned $385 for 36 boxes of cookies. what js the cost of one box of blueberry cookies and one box of blackberry cookies?

1 answer

Let's assume the number of boxes of blueberry cookies sold is x and the number of boxes of blackberry cookies sold is y.
From the problem, we have two equations:
1. x + y = 36 (the total number of boxes sold is 36)
2. 9x + 12y = 385 (the total amount earned from selling the cookies is $385)

To solve these equations, we can use substitution or elimination method.
Let's use the substitution method:
From equation 1, we have x = 36 - y.
Substituting this value of x in equation 2, we get:
9(36 - y) + 12y = 385
324 - 9y + 12y = 385
-9y + 12y = 385 - 324
3y = 61
y = 61/3 = 20.33 (rounded to 2 decimal places)

Substituting the value of y in equation 1, we get:
x + 20.33 = 36
x = 36 - 20.33 = 15.67 (rounded to 2 decimal places)

So, they sold approximately 15 boxes of blueberry cookies and 20 boxes of blackberry cookies.

Now, let's find the cost of one box of each type of cookie:
The cost of one box of blueberry cookies is $9.
The cost of one box of blackberry cookies is $12.

Therefore, the cost of one box of blueberry cookies is $9 and the cost of one box of blackberry cookies is $12.