At one farmer’s market, bananas cost $0. 80 per pound. At another farmer’s market, bananas are sold in 5-pound bags for $4. 50 per bag. Which explains how to find the better buy? Divide 4. 50 by 5 to find the unit rate for the 5-pound bag, and compare that number to $0. 80 per pound. Divide 0. 80 by 5 to find the unit rate for the 5-pound bag, and compare that number to $0. 80 per pound. Multiply 4. 50 by 5 to find the cost for 5 pounds, and compare to $4. 50 per bag. Multiply 4. 50 by 0. 80 to find the cost for 5 pounds, and compare to $4. 50 per bag.