Elwood had to retire early because of a job-related injury. During the current year, he receives $10,000 in Social Security benefits. In addition, he receives $6,100 in cash dividends on stocks that he owns and $8,300 in interest on tax-exempt bonds. Assuming that Elwood is single, what is his gross income

a. if he receives no other income

b. if he also receives $10,700 in unemployment compensation

c. if he sells some land for $79,600 and he paid $43,900 for the land