Will a one variable equation always have only one solution

You are constructing a histogram for scores that range from 70 to 100 in whole points. frequencies range from 3 to 10; that is, every whole-point score between 60 and 100 occurs at least 3 times, and at least one score occurs 10 times. which of these would probably be the best range and size for the score intervals along the x-axis?

Find the constant of variation for the relation and use it to write an equation for the statement. then solve the equation.

Last one and the bottom answer choice is y=(x-4)^2+1 you guys!