How do i find the constraint inequality??????

Question

here is the problem

You grow and sell tomatoes and green beans. It costs $20 to grow a bushel of tomatoes and it takes 3 sq. yards of land. It costs $10 to grow a bushel of beans, and it takes 6 sq. yards of land. Your budget is $80, and you have 30 sq. yards of land available. If you make $40 profit on each bushel of tomatoes and $60 profit on each bushel of beans, how many bushels of each should you grow to maximize profits?

Answer 1