You are the correct one. If the person is not able to proof, and if you are rather sure about your answer, it is better to take your own answer instead :)
-9d = 63
<Multiply both sides by (-1)>
=> (-1) × (-9d) = (-1) × 63
=> 9d = -63
=> d = -7
Answer:
Line YV.
Step-by-step explanation:
A line contains two infinite arrows, no endpoints.