What is the formula used for the web form?

I just added the formula from the web form into task the description.

dbrant opened https://github.com/wikimedia/apps-android-wikipedia/pull/4694

@HNordeenWMF This is easily done, but it actually conflicts with a minor bit of UX that we have currently, namely: when you select the checkbox to "add the transaction fee", we actually update the text field with the total amount to include the fee. But now, if the transaction fee is dependent on the amount, updating the text to include the fee becomes impossible.
Would it be acceptable to no longer update the amount that's in the text field to include the fee? (This would actually also bring it more in line with behavior on Web.)

It would be preferred to no longer update the amount that's in the text field to include the fee. That is how it happens in a web banner as well, except they have a confirmation button that shows your total with one time / monthly so there's that extra confirmation.

But could you wait to release this task? I am checking in with fundraising on the priority. Then I'd like to ensure the change happens at a similar time for iOS and Android.