Which of these systems has one unique solution?
a. 4x−3y=1 and 4x−3y=−2
b. 4x−3y=1 and 8x−6y=2
c. 4x−3y=1 and −8x+6y=−4
d. 4x−3y=1 and 4x+3y=1

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