Are you sure it is correct because for each one your just doubling the number. 2+2=4. 4+4=8. 8+8=16. I think its suppose to be 16+16= 32 and so on, but I may be wrong
Mark could travel 682.5 miles in 7.5 hours.
To solve this you have to find how fast he travels per hour.
455 miles/5 hours=91 mph
91 mph multiplied by 7.5 hours(91 x 7.5)= 682.5
682.5 Miles in 7.5 hours
Hope this helped you! :D