Suppose the government imposes a tax of 15 per cent on the first $70 000 of income and 20 per cent on all incomes above $70 000, what are the tax liability and the marginal tax rate for a person whose income is $80 000?

a.20 per cent and $10 500, respectively

b.$12 500 and 20 per cent, respectively

c.$10 500 and 15 per cent, respectively

d.both are 15 per cent