During a collision between two ice hockey players, A and B, the forces at one instant are recorded.
| record | force | magnitude | direction |
|---|---|---|---|
| R1 | force exerted by A on B | 450 N | east |
| R2 | friction exerted by the ice on B | 60 N | west |
| R3 | force exerted by B on A | not recorded | not recorded |
A student claims that R2 is paired with R1 because the forces point in opposite directions. Explain why R3, rather than R2, is paired with R1. State the magnitude and direction that should be recorded for R3.