Since the line is parallell to the x-axis we know the slope is zero: 
Using the point-slope formula we can substitute know values:
You could also jsut do it by inspection: since it passes through (3,4) and is horizontal it must cross at (0,4) i.e. all y=4.
Using the point-slope formula we can substitute know values:
You could also jsut do it by inspection: since it passes through (3,4) and is horizontal it must cross at (0,4) i.e. all y=4.