Hello , I was just made aware of your invite, I'd be happy to complete the article in the next few hours.
I wont go in detail in my proposal, to ensure you don't risk anything, you don't have to pay me until the article is finished, once its all well and good, I trust you will compensate based on your great profile.
I have been a writer for a little over a decade, so just tell me your details and I will fulfil the job.
Thanks
Ben