Question

9) Which equation represents the line that passes through the point (3,4) and is parallel to the x-axis?

A x = 4
B x = 3
C y = 4
D y = 3

Answer 1

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.