Please step by step teach me how to do this question.

I don't understand for A/c balance part and how to get margin call.

This question is already with correct answer.

Practice Problems on Futures 1. You short the S\&P500 futures contract on 1/15 when the futures price is 2810 . The initial margin is $40,000 and the maintenance margin is $30,000. Following your trade, the market moves in the following manner. a. On what day(s) do you get a margin call and what are the amounts of the margin calls