a = 4800 – 6t

b = 5400 – 8t

In the system of equations above, a and b represent the distance, in meters, two marathon runners are from the finish line after running for four hours and t seconds. How far will runner a be from the finish line when runner b passes her?

A. 300 meters

B. 500 meters

C. 100 meters

D. 3000 meters