cost of one peppermint cookies = $ 0.6
cost of one cinnamon sugar cookies = $ 0.3
Solution:
Let "p" be the cost of one peppermint cookies
Let "c" be the cost of one cinnamon sugar cookies
To find: cost of each cookie
On the first day, they sold 120 peppermint cookies and 30 cinnamon sugar cookies for a total of $81
We can frame a equation as:
120 peppermint cookies x cost of one peppermint cookies + 30 cinnamon sugar cookies x cost of one cinnamon sugar cookies = $ 81
[tex]120 \times p + 30 \times c = 81[/tex]
120p + 30c = 81 --------- eqn 1
The next day they made $60 by selling 70 peppermint cookies and 60 cinnamon sugar cookies
70 peppermint cookies x cost of one peppermint cookies + 60 cinnamon sugar cookies x cost of one cinnamon sugar cookies = $ 60
[tex]70 \times p + 60 \times c = 60[/tex]
70p + 60c = 60 --------- eqn 2
Let us solve eqn 1 and eqn 2 to find values of "p" and "c"
Multiply eqn 1 by 2
240p + 60c = 162 --- eqn 3
Subtract eqn 2 from eqn 3
240p + 60c = 162
70p + 60c = 60
(-) -------------------------
170p = 102
p = 0.6
Substitute p = 0.6 in eqn 1
120p + 30c = 81
120(0.6) + 30c = 81
72 + 30c = 81
30c = 9
c = 0.3
Summarizing the results:
cost of one peppermint cookies = $ 0.6
cost of one cinnamon sugar cookies = $ 0.3
