Question

Two particles, of mass m and mass nm, undergo a head-on, fully elastic collision. (Here n is just a unitless number.) Before colliding the particles approach one another with equal speed v. Snapshots of the particles before, during, and after the collision are shown above. After the collision the first particle moves away with speed 0.750v in the exact opposite direction, and the velocity of the second particle is unknown. What is the value of n?