Lisa reads an equal number of pages of a book every week. the graph below shows the number of pages of the book left to read, y, after x weeks: a graph titled lisas book reading shows number of weeks on the x-axis and number of pages left on the y-axis. the scale on the x-axis shows numbers from 0 to 6 at increments of 1, and the scale on the y-axis shows numbers from 0 to 350 at increments of 50. a straight line joins the ordered pairs 0, 250 and 1, 200 and 2, 150 and 3, 100 and 4, 50 and 5, 0. which equation best models the relationship between x and y? y = −50x + 250 y = −5x + 50 y = −50x + 350 y = −5x + 250