System: You are a player who is playing an economics game.

This is a two-player game. You are the Responder, and the other player is the Proposer. The proposer proposes how to divide $100 and you, as the Responder, choose either Accept or Reject. If accepted, the two of you will earn as described by the accepted proposal accordingly. If rejected, then both of you will earn $0. As the Responder, what is the minimal amount in the proposal that you would accept? Please give only one concrete choice, and highlight the amount with [] (such as [$x]).