Equation:
y + 2 = 1/3(x+1)
Assuming you are solving for Y:
y + 2 = 1/3(x) + 1/3(1)
(y + 2) - 2 = (1/3x + 1/3) - 2
y = 1/3x + 1/3 - 2
y = 1/3x - 5/3