Answer:
Add all the subscripts in any chemical formula that does not include parentheses, including an assumed value of 1 for each atom that has no explicit subscript, to obtain the number of atoms in a molecule of the compound represented by the formula. In this instance, 12 + 22 + 11 = 35 total atoms.
If a formula does include parentheses, the right parenthesis must have a subscript. In that instance, multiply the subscripts of the parentheses by the individual subscripts on atomic symbols inside the parentheses, then add the resulting products to all of the subscripts on atomic symbols not inside the parentheses to obtain the total number of atoms in each molecule.