The sample contains both Fe and oxygen
The mass of the sample is 36 g
28 g are Fe and 8 g are O
So to find the percent composition we can calculate using the following formula
Percent composition of the element = mass of the element / mass of the sample x 100%
Percent composition of Fe = 28 g / 36 g x 100 % = 77.8%
Percent composition of O = 8 g / 36 g x 100 % = 22.2%