Martha is self-employed tax accountant who drives her car to visit clients on a regular basis. She drives her car 4000 miles for business and 10,000 for commuting and other personal use. Assuming Martha uses the standard mileage method, how much is her deductible auto expense for the year? a. The deductible business auto expense is $--'--. b. where in her tax return should Martha claim this deductible? The expense should be deducted on Martha-----.