1, the time for a car to drive from the midpoint to the finish line is exactly the time for a bicycle to drive from two-fifths to the midpoint, which means that the problem of speed ratio is transformed into the problem of distance ratio at the same time.

Yes1/2: (1/2-2/5) = 5:1.

2. Let C be 1 unit, then if B is 2 A, it will be 6 or 5 days.

5*( 1+2+6)=45, and the total project is 45*3= 135. During the three days of A's rest, the work is 2+3* 1=5. At this time, there is still a workload of 135-45-5=85, and 85/9=9.44 is about 10. Finally, this project takes 5+3+ 10= 18 days. Completed on March 18.