Answer: B(4pi+8.4)h
Explanation:
The circular track is 2.Pi.r=20pi miles
Car b travels 10hours at 2mph, so when car a starts its journey its 20 miles from point x.
Both cars need to make a sum of 20pi-20+12 miles.
As car b speed is 2mph and car a 3mph we can say car b is going to make 2/5 and car a 3/5
car b will make
2/5 (pi20-8)miles=8pi-3,2 miles
The time is x/v
(8pi-3,2)miles/2mph=4pi-1,6 h
Remember that car b started 10 h before
4pi-1,6+10=(4pi+8,4)h