Pleas help me with this question

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

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?

Solve for x where 0 equation: cot^2x+2cotx+1=0