All positive numbers not including 0

How do i put 3(x+7) in distributive property

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?

If f(x)=3 over x+2 - square root x-3 then f(7)=