Explanations:

Aluminum acetate has the chemical formula Al(CH3COO)3. In 35 g aluminum acetate, there are 35 g / 204.12 g/mol = 0.171 mol aluminum acetate. Each mole of aluminum acetate contains 3 moles of carbon, so there are 3 * 0.171 mol = 0.513 mol of carbon in 35 g aluminum acetate.