Find the grams of iron in 79.2 g of Fe2O3.

First you find the RFM (Relative Formula Mass) of Fe2O3

Fe2 = 56 x 2

= 112

O3 = 16 x 3

= 48

112 + 48 = 160

Moles = mass/RFM

= 79.2/160

=0.495

Then you rearrange the formula

Mass = moles x RFM

= 0.495 x 112

= 55.44 g

(To find mass of Iron have to use RFM of total iron in the substance example Fe2 ^^)