Quadratic, exponential, and square root functions are all non-linear. They should not be straight. There is always an x and/or y value that they will never be on. Linear functions can touch all values. That sounds very confusing, but it's better than nothing, so I'm sorry.
Linear functions have a constant slope, so nonlinear functions have a slope that varies between points. Algebraically, linear functions are polynomials with highest exponent equal to 1 or of the form y = c where c is constant. Nonlinear functions are all other functions. An example of a nonlinear function is y = x^2.
If all were grandstand tickets, revenue would be 0.65*5716 = 3715.40. It was actually 298.50 less than that. Each bleacher ticket sold drops the revenue by .25, so there were 298.50/.25 = 1194 bleacher tickets sold.
