Grady received $8,480 of Social Security benefits this year. Grady also reported salary and interest income this year. What amount of the benefits must Grady include in his gross income under the following five independent situations? (Leave no answer blank. Enter zero if applicable.)

a. Grady files single and reports salary of $12,800 and interest income of $320.

b. Grady files single and reports salary of $22,770 and interest income of $670.

c. Grady files married joint and reports salary of $76,400 and interest income of $570.

d. Grady files married joint and reports salary of $44,000 and interest income of $770.

e. Grady files married separate and reports salary of $22,770 and interest income of $670.