Lillian has set up a lemonade stand outside her house and sells small cups and large cups of lemonade. Each small cup holds 10 ounces of lemonade and each large cup hold 24 ounces of lemonade. Lillian used 580 ounces of lemonade and sold twice as many large cups as small cups. Write a system of equations that could be used to determine the number of small cups sold and the number of large cups sold. Define the variables that you use to write the system.