Content writer

We are looking for a long-term writer. We need articles ( ---------- words each) in a given niche with given keywords.
We expect 20 articles every week.
Our budget is 300$ for 80 articles a month.
What is your experience in content writing?
Can you send the latest article you wrote?
Do you have experience with WordPress and SEO?
Can you write an article to qualify you for my needs?
The article should contain 500 words and based on the provided keyword.