(opening wip+output-closing wip)-opening wip=units started andcompleted

这个公式怎么理解？

这个公式是错的！

Yes, it is wrong.

Opening WIP + Input units - closing WIP = finished output

Guess you want to know the fully worked units or units started andcompleted

Fully worked units = Input units - closing WIP 

                        OR= finished output - opening WIP

Hope it is clear now