Sally teaches elementary school and is given $320 to spend on books for her students. A reading book costs $12 and there are 30 students in her class. Unfortunately, if the money she is given by the school to pay for books is not sufficient, she will need to pay the rest out of pocket. How much money does Sally need to pay out of pocket, to buy every student a reading book?
To purchase a book for each student, Sally needs: 30 x $12 = $<<30*12=360>>360.
She thus needs to pay $360 - $320 = $<<360-320=40>>40 out of pocket.
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Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
You are solving math problems. Here are some examples of how to solve the task:

John and Yasmin's dad is named Gabriel. If John has twice the number of children that her sister has and Gabriel has six grandkids, how many children does Yasmin have?We don't know Yasmin's number of children yet, but let's represent it as Y.
If John has twice the number of children Yasmin has, then John has 2*Y = 2Y kids
If Gabriel has 6 grandkids between John's and Yasmin's children, then we can represent this as 6 = 2Y + Y
If we solve the latest equation then we learn that 6=3Y
Given that Y represents how many kids Yasmin has, then solving for Y we know that Y=6/3 or Y=2 kids
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LaKeisha is mowing lawns to raise money for a collector set of books. She charges $.10 for every square foot of lawn. The book set costs $150. If she has already mowed three 20 x 15 foot lawns, how many more square feet does she have to mow to earn enough for the book set?She has mowed 900 square feet because 3 x 20 x 15 = <<3*20*15=900>>900
She has earned $90 because 900 x .1 = <<900*.1=90>>90
She has to earn $60 more dollars because 150 - 90 = <<150-90=60>>60
She has to mow 600 more square feet of lawns because 60 / .1 = <<60/.1=600>>600
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Now, solve this next question in the style of the above examples:

Sally teaches elementary school and is given $320 to spend on books for her students. A reading book costs $12 and there are 30 students in her class. Unfortunately, if the money she is given by the school to pay for books is not sufficient, she will need to pay the rest out of pocket. How much money does Sally need to pay out of pocket, to buy every student a reading book?

### Response:
To purchase a book for each student, Sally needs: 30 x $12 = $<<30*12=360>>360.
She thus needs to pay $360 - $320 = $<<360-320=40>>40 out of pocket.
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