Incorrect Business Use Calculation - Supplemental Expense Worksheet -- Car & Truck Expense

After the percent of business use is calculated based on the miles entered, if the vehicle was not used for 12 months of the year, then there is an additional calculation to account for the months of business use.  Based on your entry in line 10b, the vehicle was used for business purposes for 5 months so there is an additional calculation to be made.

The information below is from the TurboTax help content with regard to calculating line 9:

Line 9: Percentage of business use
The program divides lines 6 by line 5c (then multiplies the result by line 10b divided by 12 months, if line 10b has an entry).