Zoom in if unclear. Hope this helps. The table of x and R may not need to be presented in your working but it helps you to understand that the pattern of R, as x varies, is not linear but quadratic. And also, if question mentioned to find a function for the revenue... in terms of the price of a ticket, this also translates to saying finding a function for Y (Dependent variable) in terms of X (Independent variable). That is how I started my solution by stating clearly my X and Y variables, knowing which is dependent and which is independent.