To find the other line's slope, take the "opposite reciprocal"
For example, if the slope is -1/3, you change the negative sign to positive and you take the reciprocal.
-1/3 --> +3/1
The slope of the perpendicular will be positive 3. To find the equation that passes through the point (1,5), substitute the x and y values into the equation y=mx+b and solve for b, because you know the slope already, now you have to find the y-intercept (the b in the equation).
5=3(1)+b
5=3+b
5-3= 3-3+b
2=b
The equation of the perpendicular line is y=3x+2
