Marcelina uses a blend of white corn and yellow corn to make tortilla chips at her restaurant. She needs to buy 50\,\text{kg}50kg50, start text, k, g, end text of corn in total for her next order. White corn costs \$0.30$0.30dollar sign, 0, point, 30 per kilogram, yellow corn costs \$0.15$0.15dollar sign, 0, point, 15 per kilogram, and she wants to spend \$12$12dollar sign, 12 total.
Here's a graph that shows a system of equations for this scenario where xxx is the amount of white corn she buys and yyy is the amount of yellow corn she buys.