Тестовое задание

Countries A, B and C produce only watermelons (X) and grapefruits (Y). The production possibility frontiers are given by: X_A+Y_A=100, 2X_B+3Y_B=300, X_C+2Y_C=600. What is the maximum amount of watermelons that they can produce together if they want to produce at least 200 grapefruits?