Game theory, please solve the question

2 Modified Ultimatum Consider the following modified ultimatum game, involving a Proposer and a Responder. The Proposer is given $100, and moves first, deciding how much, x, to give the Respon der. The Responder either Accepts or Rejects the Proposer's offer. If the offer is accepted, then the Proposer gets 100-x, and the Responder gets c. If the offer is rejected, then the Responder gets 0, and the Proposer gets -$1. (a) Draw the game tree. (b) What is the SPNE? What are the Nash equilibria? (c) When we run the ultimatum game in experiments, we typically find that x