Determine the taxpayers current-year (1) economic income and (2) gross income for tax purposes from the following events:

Curtis, age 18, has income as follows: $700 interest from a certificate of deposit and $6,000 from repairing cars.

Mattie, age 18, has income as follows: $600 cash dividends from a stock investment and $4,700 from handling a paper route.

Mel, age 16, has income as follows: $800 interest on a bank savings account and $700 for painting a neighbors fence.

Lucy, age 15, has income as follows: $400 cash dividends from a stock investment and $500 from grooming pets.

Sarah, age 67 and a widow, has income as follows: $500 from a bank savings account and $3,200 from babysitting.

Please explain the thought process for determining the economic income and gross income for each example.