Linear Function y=mx+b: Converting between graphs and equations

Choose the appropriate function for the number line 4.

$y=x$

Which function corresponds to the line marked $IV$?

$y=-x+1$

Which function corresponds to the line marked $\text{III}$?

$y=-x+4$

Which function corresponds to the line marked $\text{II}$?

$y=x-1$

Which function corresponds to the line marked $\text{I}$?

$y=x+4$

Which function describes the line numbered 1?

$y=-x$

Which function describes the line numbered 2?

$y=-6x$

Which function represents line 3?

$y=6x$