How can one variable equations have more than one solution in some cases and no solutions in others?

What is the difference between the points (4, 7) and (4, -5)? a. 0 units b. 2 units c. 4 units d. 12 units

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?

A10 inch cookie cake is divided into 8 slices. what is the area of 3 slices