Mr. Ellis has started a vegetable garden. He bought 15 bags of soil and 3 bags of fertilizer for $282.72. He realized he didn't have enough supplies, so he bought another 5 bags of soil and 2 bags of fertilizer for $107.23. What was the cost of each bag of soil and fertilizer? Let the cost of each bag of soil = z and the cost of
each bag of fertilizer = y.