PLEASE HELP!!!

1) Write the equation of the line that passes through points (3,6) and (5,18) using function notation.

f(x)=2x+12
f(x)=6x-12
y=2x+12
y=6x-12

2) Choose the equation of the horizontal line that passes through the point (2,4).

y=2
x=2
y=4
x=4