*Perpendicular lines always have the opposite slope (meaning that you have to switch the numerator and denominator) and sign when comparing to the given equation.
To start off, convert the equation to be formatted into y=. You do this by first subtracting the 3x from both sides of the equation so that it now reads . Now, divide the whole equation by three in order to get rid of the value attached to the y. The equation should now read to be: . Now, just switch the the slope into its opposite (which is the reciprocal) and switch the negative sign into a positive.