Answer:
Th answer is: Marginal tax rate for Family A is 20%, average tax rate is 12%. There is no Family B in the question.
Step-by-step explanation:
Family A's tax rate are as follows:
Income Tax rate
up to $10,000 0%
$10,000 to $30,000 10%
$30,000 to $50,000 20%
$50,000 to $80,000 30%
over $80,000 40%
Since Family A's income is $50,000, their marginal tax rate is 20%, and its average tax rate is = [($20,000 x 10%) + ($20,000 x 20%) / $50,000] = ($2,000 + $4,000) / $50,000 = $6,000 / $50,000 = 12%