Given: 3x + y = 1.

Solve for y.

A. y = - 3x + 1

B. y = - 3x - 1

C. y = 3x - 1

Y=-3x+1

So the answer is A. All you're doing is moving the 3x to the opposite side, and because your switching the side, you need to switch the sign. So it's a negative 3x after you solve for y. Solving for y (or any letter) is just getting that letter alone on one side of the equal sign.