Magnesium replaces silver in a single replacement reaction between magnesium and silver nitrate. If 32g of Ag

were produced as a result, how many atoms of magnesium were used?

Mg+2AgNO3--->Mg(NO3)2+2Ag

You are welcome :)
Now allow me to also help you with this question.
First write the balanced chemical equation:
Mg + 2AgNO3 ---> Mg(NO3)2 + 2Ag
The molar mass of Ag is 107.86 g/mol so use stoichiometry to determine the number of moles of in 32g Ag:
32g Ag / 107.86g/mol Ag = 0.297 moles Ag
For every 2 moles Ag produced, 1 mole of Mg is consumed.
So .297 moles Ag/ 2 = 0.148 moles Mg consumed.
Remember avagadro's number, 6.022E23 atoms of Mg are in 1 mole of Mg.
So just multiple the number of moles by 6.022E23 to determine the number of atoms of Mg that were used:
0.148 moles Mg x 6.022E23 atoms Mg = 8.93E22 atoms Mg were used in this reaction.

Ratio is: 1:1
Moles of Mg used = 32 /108 = 0.296 No of atoms = 0.296 x 6.022x10^23 = 1.78 x10^23