The molar mass of Al2O3 is 101.96 g/mol. The molar mass of Al is 26.98 g/mol.

The number of moles of Al2O3 in 286 g is 286 g / 101.96 g/mol = 2.81 mol.

The number of moles of Al in 2.81 mol of Al2O3 is 2.81 mol x 2 = 5.62 mol.

The mass of Al in 5.62 mol is 5.62 mol x 26.98 g/mol = 151.6 g.

Therefore, there are 151.6 g of Al in 286 g of Al2O3.