Paul Is Employed as an Auditor by a CPA Firm

Short Answer

Paul is employed as an auditor by a CPA firm. On most days, he commutes by auto from his home to the office. During one month, however, he has an extensive audit assignment closer to home. For this engagement, Paul drives directly from home to the client's premises and back. Mileage information is summarized below:
If Paul spends 20 days on the audit, what is his deductible mileage?