Nguyen can earn $5 and hour for working at the college library and $9 an hour for construction work. to save time for study, he wants to limit his work to 20 hours a week but still earn more than $125. how many hours can he work in the library?

The answer is 13 days.

Step-by-step explanation:

Let's call the days he can work in the library x.

The days he can work in construction work is 20-x. Then x days per 5$ plus (20-x) days per 9$ should be bigger than 125$.

therefore

Since x must be integer, the biggest we choose is 13.

To crosscheck

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5+2x=a

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