What do I put in the blanks??

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?

How can you use synthetic substitution to tell whether a given binomial is a factor of a polynomial?

What is the domain of the step function f(x)=[2x]-1?