Jenny is picking apples to make apple pie. The amount of apples that she needs to pick varies directly with the
number of pies she plans to bake. If Jenny needs to make 12
apple pies, she will need to pick 42 apples. How many apples
would she need to pick if she was only making 8 pies?

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).