The equation of a perpendicular line can be found by swapping the x- and y-coefficients and negating one of them. The constant will be chosen to match the given point.
Swapping coefficients, we get ...
-3y = x + c
Negating the y-coefficient gives ...
3y = x + c
Filling in the given point, we have ...
3(5) = -1 + c
16 = c
The equation of the perpendicular line can be written as ...
3y = x + 16 . . . . matches choice A
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Note that choice A is the only equation that gives a line with positive slope. The given equation has negative slope, so its perpendicular must have positive slope.
