Astore sold 70 copies of a magazine for $350. each copy of the magazine costs the same. which equation and set of ordered pairs best represents the price (y), in dollars, of a certain number of copies (x) of the magazine? a. y = 3x; (1, 3), (2, 6), (3, 9) b. y = 4x; (1, 4), (2, 8), (3, 12) c. y = 5x; (1, 5), (2, 10), (3, 15) d. y = 6x; (1, 6), (2, 12), (3, 18)