Dennis is a self-employed hair stylist who operates a salon in his home. The property taxes and interest allocated to the business amount to $5,000, maintenance and utilities allocated to the business total $2,100, and depreciation allocated to the business use of the home equals $3,100 for the current tax year.

a. If Dennis' gross revenue after deducting supplies for his business is $5,900 for the current tax year, calculate his allowable deductions for the home office.

b. If Dennis' gross revenue after deducting supplies for his business is $13,800, calculate his allowable deductions for the home office.