Line a and b are perpendicular
Every time the line is vertical, the slope is ‘no slope or undefined’.
I believe the answer is d
<h3>
Answer:</h3>

<h3>
Step-by-step explanation:</h3>
In this question, we're simply combining "like-terms" in order to simplify the expression.
Lets solve:

When you're done solving, you should get -17x-21
This means that -17x-21 would be the simplified version.
<h3>I hope this helped you out.</h3><h3>Good luck on your academics.</h3><h3>Have a fantastic day!</h3>