Suppose the tax rate on the first $10,000 of income is zero; 10% on the next $20,000; 20% on the next $20,000; 30% on the next $20,000; and 40% on income over $70,000. Family C has an income of $100,000. What is family C's average tax rate?

Group of answer choices

20%

22%

40%

30%