The percent composition of a compound is the percentage by mass of each element in the compound. To calculate the percent composition of the compound, we first need to find the mass of each element in the compound.

The mass of iron in the compound is 17.6 g.

The mass of sulfur in the compound is 10.3 g.

The total mass of the compound is 27.9 g.

The percent composition of the compound is:

% iron = (mass of iron / total mass of compound) * 100%

= (17.6 g / 27.9 g) * 100%

= 63.1%

% sulfur = (mass of sulfur / total mass of compound) * 100%

= (10.3 g / 27.9 g) * 100%

= 36.9%

Therefore, the percent composition of the compound is 63.1% iron and 36.9% sulfur.