The sum of three numbers is 6. The first, minus the second, plus 3 times the third, is 12. The third, plus 4 times the first, plus the second, is 21. What are the numbers?

How much money does ron have left each month after his fixed expenses? ron graduated from college five years ago. he recently bought a house, but shares it with a housemate who pays him $800 a month for rent and utilities. ron is putting a budget worksheet together so he will have a better idea of where his money is going and where he can save. enlarge