Bartolo is running a race. He determines that if he runs at an average speed of 15 feet/second, he can finish the race in 6 seconds. If he runs at an average speed of 18 feet/second, he can finish the race in 5 seconds.

Bartolo thinks that the fastest he can run is 30 feet/second. How long would it take him to finish the race at this speed?

A.
2 seconds
B.
2.5 seconds
C.
3 seconds
D.
3.5 seconds