Sorry I was moving around taking the picture and my handwriting is sloppy. But I hope you understand how I got the answer
Answer:
5x -
= 
Step-by-step explanation:
His average speed will be 75 miles per hour. Hope it help!

The formatting was a bit confusing, so please do let me know if this isn't the correct equation for the sequence.
The first term is given, which is

Now, use the equation for the next terms:



Thus, the first 4 terms are -9, -8, -6, and -3. Let me know if you need any clarifications, thanks!