at the grocery store, vern buys 4 avocados, 4 pounds of bananas, and 4 pounds of cherries. The total cost is $22. The following week it costs vern $6 to buy 1 avocado, 2 pounds of bananas, and 1 pound of cherries. The week after, vern spends $15 to purchase 2 avocados, 4 pounds of bananas and 3 pounds of cherries. How much woud it cost to buy 3 avocados, 1 pound of bananas, and 2 pounds of cherries