Christopher has set up a lemonade stand outside his house and sells small cups and large cups of lemonade. Each small cup holds 10 ounces of lemonade and each large cup hold 20 ounces of lemonade. Christopher used 800 ounces of lemonade and sold twice as many small cups as large cups. Graphically solve a system of equations in order to determine the number of small cups sold, x, and the number of large cups sold, y.
