Find equation where line passes through (7,8) and perpendicular to line y=8

Since in y=8, the slope is 0 (because there is no x) and b is 8 in y=mx+b, we know that the perpendicular line is x = (something) because the perpendicular lines of y = are x = due to that y = equations are strictly horizontal while x = equations are strictly vertical. Since we know that x = has to pass through (7, 8), x = 7