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?