Hello,
To start, we have to identify the slope of the perpendicular line. Perpendicular lines have opposite reciprocal slopes. Therefore, the slope of our new line will be 1/4.
Now, just substitute in the given point with our new slope and we can solve for B.
y = (1/4)x + b
1 = (1/4)5 + b
1 = 5/4 + b
-1/4 = b
Now that we have the slope and the y-intercept, we can put together our equation.
It is: y = (1/4)x - 1/4
Good luck,
MrEQ