If you are saying that you sold $93 , was that the cost of the items you sold or was that your revenue (the amount you received). If it was the cost of the items you sold, then yes that would be how to get to ending inventory. Actually the opposite of what you wrote (3800-93).
However, you may have to circumstances like theft that may affect ending inventory. If there was no theft or did not use it for personal life, then the ending inventory would be the beginning inventory minus the cost of the items you sold.
