A line parallel to the x axis is another vertical line: y=a. Since a point on this line is (2,5) a=2. The line is y=5

Here's another way to find it.

y - y(1) = m(x-x(1)) is the slope point equation of a line with slope m and a point (x(1),y(1)).

y - 5 = 0 (x-2)

y-5 = 0

y = 5