Tony and Maria are training for a race by running all the way up and down a 700\:m long ski slope. They each run up the slope at different constant speeds. Coming down the slope, each runs at double his or her uphill speed. Maria reaches the top first, and immediately starts running back down, meeting Tony 70\:m from the top. When Maria reaches the bottom, how far behind is Tony?
Answer Choices
A. 140\:m
B. 250\:m
C. 280\:m
D. 300\:m
E. 320\:m