Which of these lines is perpendicular to the line x−3y=4x - 3y = 4x−3y=4?
y=3x+1y = 3x + 1y=3x+1
y=−3x+1y = -3x + 1y=−3x+1
y=13x+1y = \frac{1}{3}x + 1y=31x+1
y=−13x+1y = -\frac{1}{3}x + 1y=−31x+1