You sell one December futures contract when the futures price is $1,010.00 per unit. Each contract is on 100 units and the initial margin per contract that you provide is $2,000. The maintenance margin per contract is $1,500. During the next day the futures price rises to $1,020.60 per unit. What is the balance of your margin account at the end of the day?

ANS=2,000 just don't know how to get it- thanks