If f(x+3)=2x-1 for all values of x, what is the value of f(-5)?

clearly if we want to have f(x+3) have -5 in the argument, we must have x + 3 = -5, meaning that x = -8. therefore

f(-8+3) = 2(-8) - 1

f(-5) = -16 - 1 = -17

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).