When clothes are sold by an second hand store, the store takes some of the money, and the donor gets the rest. The graph below shows how much money a donor makes given the total amount of money brought in by the second hand store from sales of a piece of clothing. Identify the constant of proportionality between dollars earned by the donor and dollars brought in by the second hand
store.
Write an equation relating dollars earned by second hand store, , to dollars earned by the donor, x.