The equation for speed is s=d/t, s=276/6.5. Then, you divide 276 in 6.5: s is approximately 42 miles/hour. So, he drove 12 miles/hour faster getting there than coming back home.
-144 is undefined I just did this like a min ago lol but hope this works out for you if so leave a like and see if you have other questions thanks for using Brainly