Kassie owns a food truck that sells pasta bowls and meatball sandwiches. She sells each pasta bowl for $5.50 and each meatball sandwich for $6.75. Yesterday Kassie made a total of $760 in revenue from all pasta bowls and meatball sandwiche sales and there were three times as many meatball sandwiches sold as there were pasta bowls sold. Write a system of equations that could be used to determine the number of pasta bowls sold and the number of meatball sandwiches sold. Define the variables that use to write the system.