Whatever you intended to type before the 'x' . . . " -1.2 " or " - 1/2 " . . .
that's the slope of the line represented by the equation.
A line perpendicular to it has a slope with the negative reciprocal of this one.
So the perpendicular line would be
y = 0.8333 x (negative reciprocal of -1.2) + any number
or
y = 2 x (negative reciprocal of - 1/2) + any number