Find the molar mass of Iron
55.845 g/mol
Take the 5.5g (what you have) and put it in the numerator
Take the 55.845g/mol (molar mass) and put it in the denominator
$${\frac{{\mathtt{5.5}}}{{\mathtt{55.845}}}} = {\mathtt{0.098\: \!486\: \!883\: \!337\: \!81}}$$
There are 0.098 moles in 5.5g of Fe (iron)