Suppose we short 100 shares of a stock at $50 a share using 80% margin. If the initial margin is 50% and the maintenance is 30%, determine whether we will receive a margin call when the price is at $70. If yes, how much money do we need to put in assuming we need to pull back to the initial margin level?

In the first part of 5000 + X - 5000/5000 how do I solve for X. What does X equal in this case. Will upvote for correct response. Thank You.