Question

Duncan's Bakery sold one customer 1 dozen chocolate cookies and 10 dozen oatmeal cookies

for $49. The bakery also sold another customer 1 dozen chocolate cookies and 9 dozen
oatmeal cookies for $45. How much do the cookies cost?
A dozen chocolate cookies cost $
and a dozen oatmeal cookies cost $

Answer 1

Dozen Oatmeal = $4 and Dozen Chocolate = $9

Explanation:

Dozen Oatmeal:

10 dozen oatmeal and 1 dozen chocolate =$49

9 dozen oatmeal and 1 dozen chocolate = $45

The second customer bought 1 less dozen and paid $4 fewer dollars, therefore 1 dozen oatmeal must equal $4

Dozen Chocolate: let C = 1 dozen chocolate

10 dozen oatmeal + 1 dozen chocolate = $49

(10 x $4) + C = $49

$40 + C = $49

-40 -40

C = $9

1 dozen chocolate cookies = $9