Answer:
A bag of pop corn costs $8, and each Pretzel costs $4.25.
Explanation:
Let
be the price of popcorn, and
the price of Pretzels. If the girl bought 2 bags of popcorn and 5 Pretzels and it cost her $37.25, we have the equation
(this says that the cost of 2 popcorn bags plus 5 pretzels equals $37.25) .
And, since Zoe bought 8 popcorn bags and 9 Pretzels with a total price of $102.25, we get the equation
(this says that the cost of 8 popcorn bags plus 9 Pretzels equals $102.25).
Thus, we have two equations
1.
![2b+5p=37.25](https://img.qammunity.org/2021/formulas/mathematics/middle-school/9lkam25w1yuyetg2ylbjl7cvhtupcnryu8.png)
2.
![8b+9p=102.25](https://img.qammunity.org/2021/formulas/mathematics/middle-school/8bztv69yedk29hp0x2mq54pciaptnsuhjj.png)
and we solve them by first multiplying equation (1) by 4:
,
and then subtracting it from equation (2):
![\:\:\:\:\: 8b+9p=102.25\\-(8b+20p=149)\\\line(1,0){3 cm}\\-11p=-46.75\\\\\boxed{p=\$4.25}](https://img.qammunity.org/2021/formulas/mathematics/middle-school/d9h9pr8z3u3mc0zz4ocs2w2w6xh8l2afts.png)
Now we put this value of
into equation (1) and get:
![2b+5(4.25)=37.25](https://img.qammunity.org/2021/formulas/mathematics/middle-school/upssh6l01ixy0cr0qle0vjcjdikd3h7ggc.png)
and we solve for
to get:
![2b=37.25-21.5](https://img.qammunity.org/2021/formulas/mathematics/middle-school/7ridyho468ik2jjp1scnvhgima90thhws7.png)
![\boxed{ b=8}](https://img.qammunity.org/2021/formulas/mathematics/middle-school/k0czq2zikafhn27ui2aenuqpneydn8b7kg.png)
Therefore, a bag of popcorn costs $8, and each Pretzel costs $4.25.