Suppose the Tax Rate on the First $10,000 Income Is

Suppose the tax rate on the first $10,000 income is 0 percent; 10 percent on the next $20,000; 20 percent on the next $20,000; 30 percent on the next $30,000; and 40 percent on any income over $80,000. Family A has income of $40,000 and Family B has income of $100,000. What is the marginal and average tax rate for each family?

A) Family A: marginal-10 percent; average-10 percent; Family B: marginal-30 percent; average-30 percent.
B) Family A: marginal-20 percent; average-10 percent; Family B: marginal-40 percent; average-23 percent.
C) Family A: marginal-20 percent; average-20 percent; Family B: marginal-40 percent; average-40 percent.
D) Family A: marginal-20 percent; average-15 percent; Family B: marginal-40 percent; average-20 percent.