What is probability, include the ration

How do you solve a question like this?

Ten times the square of a non-zero number is eqaul to ninety times the number

Jessica is organizing a guided tour of the rain forest. the average profit per person that the touring company makes is given by the rational expression 18x+35/x, where x is the number of people going on the tour. what does the numerator of this rational expression represents?