A group of students launch a model rocket from the top of a building. The
students have determined the equation y =-½(x+6)(x - 18) to describe the
height of the rocket above ground level, y, in metres, at any time, x, in seconds. Complete the following table of values to predict the flight of the rocket.

answer: x=60

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).