Reflection of a straight line: ACT Math Practice Question

Try this ACT math practice question on what happens to the y-intercept of a line when it is reflected.

In the standard $xy-$coordinate plane, the line $3x – y = 6$ is reflected across the $x-$axis. What is the $y-$intercept of the resulting line?

1. $\quad -6$
2. $\quad -2$
3. $\quad 2$
4. $\quad 3$
5. $\quad 6$

Choice E