You can make it with 10 because 10%times 5% is 50%
Firstly figure out how much money you earn per one hour. This is 312$ divided by 20 is 16$/hour. Then write an equation which represents only hourly earnings: y = 16x. To answer the last question just enter the value for variable x = 15, and you will get money earned per one week.
Answer:
that library has only 3 books? it needs to open a book raising fund