Jethro has to pay his annual taxes. He knows that his tax rate is 27% of his taxable income. If he made $68,000 last year, which proportion should he use to determine how much he owes in taxes?
a. x 68000 = 27 100
b. 27 68000 = x 100
c. x 68000 = .27 100
d. 68000 x = .27 100