Ella wants to buy apples and strawberries to make a fruit tart. Apples cost 3.50 per pound and strawberries cost 3.75 per pound. How many pounds of fruit does she buy if she buys 0.5 pounds of apples and 1.5 pounds of strawberries? How many pounds of fruit does she buy if she buys x pounds of apples and y pounds of strawberries?