Deb earned a total of $20 by selling 10 cups of lemonade. After selling a total of 14 cups of lemonade, how much money will Deb have made in all? Assume the relationship is directly proportional.
Deb would have made $18 from selling 14 cups of lemonade. She earned $20 for selling 10 which is $2 per cup. Add $2 dollars for 4 more cups which makes $18