Skater 1, who has a mass of 100 kg, and Skater 2, who has a mass of 50 kg, are initially at rest on a horizontal ice rink where friction is negligible. Skater 1 pushes Skater 2, causing both skaters to move away from each other. While the skaters are in contact and pushing, how do the magnitude of the force Skater 1 exerts on Skater 2 (F12) and the magnitude of the force Skater 2 exerts on Skater 1 (F21) compare, and how do the magnitudes of their accelerations (a1 and a2) compare?