When using the inspection method, which number would you add to (and subtract from) the constant term of the numerator in this expression so the polynomial in the numerator will have (x+4) as a factor? x^2+7x+15/x+4

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?