Question：

Ask and be perpendicular to the straight line of $y = x -1$ and lead the straight line equation that cross a point {4,3}.

My method is:

{eqn = y == x - 1, pt = {4, 3}}
eq = # == 0 &@(eq /. Equal -> Subtract)
line = Cross@(Coefficient[eq[[1]], #] & /@ {x, y}) . {x, y} + c == 0
sol = First@(line /. Thread[{x, y} -> pt] // Solve)
line = line /. sol // Simplify // SubtractSides

Are there other methods to solve this problem?