Which statement can you use to conclude that the relationship must be non-proportional

Given f(x) = 17-x^2what is the average rate of change in f(x) over the interval [1, 5]?

An appliance store sells a washer-dryer combination for $1800. if the washer costs $300 more than the dryer, find the cost for each appliance.

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.