There is a handling fee for a single order, so your loss is handling fee+price difference+floating profit and loss.

The floating profit and loss on your book is -490, so once you do it, your loss is 490+ commission+price difference.

If you close your position, it is 307 1-490. After deducting the handling fee and spread, the rest is your real balance.

In addition, some commonly used formulas are given: balance = net value+floating profit and loss.

Net value = available profit+occupied profit