You know b=-6 and since you know this, you can plug -6 in for b.
This would become 4(-6) + 6 divided by 6.
You can then multiply 4 and -6 together,
-24 + 6 / 6
You can then add -24 and 6 together,
-18/6
You can then divide -18 by 6,
-18/6=-3
-3 is your final answer
