cost of one peppermint cookies = $ 0.6
cost of one cinnamon sugar cookies = $ 0.3
<h3><u>Solution:</u></h3>Let "p" be the cost of one peppermint cookies
Let "c" be the cost of one cinnamon sugar cookies
<u><em>To find: cost of each cookie</em></u>
<h3><u><em>On the first day, they sold 120 peppermint cookies and 30 cinnamon sugar cookies for a total of $81</em></u></h3>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
120p + 30c = 81 --------- eqn 1
<h3><u><em>The next day they made $60 by selling 70 peppermint cookies and 60 cinnamon sugar cookies</em></u></h3>70 peppermint cookies x cost of one peppermint cookies + 60 cinnamon sugar cookies x cost of one cinnamon sugar cookies = $ 60
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
<h3>p = 0.6</h3>Substitute p = 0.6 in eqn 1
120p + 30c = 81
120(0.6) + 30c = 81
72 + 30c = 81
30c = 9
<h3>c = 0.3</h3><u><em>Summarizing the results:</em></u>
<em>cost of one peppermint cookies = $ 0.6</em>
<em>cost of one cinnamon sugar cookies = $ 0.3</em>