Mary hernandez had a policy with a $500 deductible which paid 80% of her covered charges less deductible. she had medical expenses of $10,000.00

First, you take the $500 off the top.  The take 80% off $9500 so the company's share is $7600, Mary's copay is $2400, and her total cost is $2900 when you add the deductible back in.