An old asteroid is found. A rock from it yields 1.84 g of 238U92 and 4.22 g of 206Pb82. The molar mass of 206Pb82 is 205.974 g/mol, the molar mass of 238U92 is 238.029 g/mol, and the half-life of 238U92 is 4.46 x 109 years.
How old is this asteroid? Express your answer with the appropriate units.