Since the line is parallell to the x-axis we know the slope is zero: \(m=0\)
Using the point-slope formula we can substitute know values:
\(y=mx+b\)
\(4=0(3)+b\)
\(b=4\)
\(y=0x+4\)
\(y=4\)
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.
