Please solve NOT using excel.

Short Sell On Dec 1 2020, you sold short 4000 shares of AMC's stock at $5 per share. You put 60% cash as initial margin into the short sell account, and the maintenance margin is 30%. On Feb 1, price goes up to $19.90. 1. What is initial equity you put into the short sell account? 2. If you close this position on Feb 1, what is your net profit/loss and return? 3. If you don't want to close this position on Feb 1, how much more money ($x)should you put again to maintain the 30% margin