Compute the 2018 standard deduction for the following taxpayers.
a. Margie is 15 and claimed as a dependent by her parents. She reports $800 in dividends income and $1,400 in wages from a part-time job.
b. Ruby and Woody are married and file a joint tax return. Ruby is age 66, and Woody is 69. Their taxable retirement income is $10,000.
c. Shonda is age 68 and single. She is claimed by her daughter as a dependent. Her earned income is $500, and her interest income is $125.
d. Frazier, age 55, is married but is filing a separate return. His wife Emma itemizes her deductions.