A mass m1 15.0 kg traveling East at 12.0 m/s undergoes an elastic, head on, collision with a mass m2 traveling West at 14.0 m/s. After the collision mı is traveling West at 10.0 m/s. What was the mass of m2?
A. 5.00 kg
B. 82.5 kg
C. 7.50 kg
D. 11.0 kg