Somebody can help me plz? It seems easy for y’all but not for me haha

Use sigma notation to represent the following series for 9 terms.

Which of the functions below could have created this graph?

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?