Its slope must be the negative reciprocal of the slope of the given line.
m = -1/5
Knowing m and a given point, we can easily write the equation of the line in point-slope form.
y - y1 = m(x - x1)
y1 = -13
x1 = 11
y + 13 = (-1/5)(x - 11)
Set x = 0 to find the y-intercept b.
b + 13 = (-1/5)(0 - 11)
Solve for b. You can finish from here.