Mrs. Singer owns a profitable sole proprietorship. For each of the following cases, use a Schedule SE, Form 1040, to compute her 2015 self-employment tax and her income tax deduction for such tax.

a. Mrs. Singer's net profit from Schedule C was US$51,458. She had no other earned income.

b. Mrs. Singer's net profit from Schedule C was US$51,458, and she received a US$80,000 salary from an employer.

c. Mrs. Singer's net profit from Schedule C was US$51,458, and she received a US$127,000 salary from an employer.