Can some help me revise this sentence to eliminate jargon and use short familiar words? I just need to see how one is done so I can complete the rest of the questions myself.

With regard to the aforementioned letter of July the 15th we expect to expedite your order to ship no later than July 21. Your affirmation via signature will conclude all manner of business regarding this transactions.

We'll send your order no later than July 21. Your signature that you've received it, will complete this transaction.

So I don't have to mention the letter at all?

I don't think it's necessary.

Of course! Here's a revised version of the sentence using simplified language:

Regarding the letter we mentioned on July 15th, we plan to send your order by July 21 at the latest. Once you sign to confirm, everything related to this transaction will be completed.

Remember, when simplifying sentences and eliminating jargon, it's important to break down complex or technical terms into simpler, more familiar words while maintaining the original meaning of the sentence.