As the question says, we are going to follow the path of the hint, first by finding the number of moles of Sulfur in 3.75 grams, and we can do that by using its molar mass, which is 32g/mol
32g = 1 mol
3.75g = x moles
32x = 3.75
x = 3.75/32
x = 0.12 moles of Sulfur in 3.75 grams
Now we have the number of moles, and to find the number of atoms, we need to use the Avogadro's constant number, which is the number of atoms in a single mol, this value is 6.02*10^23 atoms in 1 mol
1 mol = 6.02*10^23 atoms
0.12 moles = x atoms
x = 7.22*10^22 atoms of Sulfur in 3.75 grams