So the slope of the first line is 4/3. If this line is perpendicular, then you have to flip it and switch the sign (flip it n switch it (how I remember it)). So the slope of the new line is -3/4. Then you have to plug in the point you're given and the new slope. Use y=mx+b format. -1=-3/4*-4+b Then solve for b. -3/4*-4 is 3. -1=3+b Subtract 3 from each side. -4=b. So now you have the y-intercept and slope. All you have to do is plug it in. y=-3/4x + -4 or y=-3/4 - 4 There's your answer!