To two lines be perpendicular theirs angular coeficients needs to be the opposite inverse, so, we have the line 2x - 7y = 0 => 7y = 2x => y = 2x/7 it have a 2/7 angular coeficient, so the other line need to be the opposite inverse, and it's -7/2
Let's discover the other line:
(y - yo) = m.(x - xo)
(y - 5) = -7/2.(x - 2)
y - 5 = -7x/2 + 7.2/2
y - 5 = -7x/2 + 7
y = -7x/2 + 7 + 5
y = -7x/2 + 12
Let's multiply all the equation by 2.
2y = -7x + 24
Pass -7x
7x + 2y = 24
7x + ky = b
b is 24 and k is 2
