To calculate this, we need to multiply the number of atoms of each element by the number of molecules of that element in the compound.

There are 3 iron (Fe) atoms in 3Fe(OH)3, and each iron atom has an atomic number of 26. So, there are a total of 3 x 26 = 78 iron atoms in 3Fe(OH)3.

There are 9 oxygen (O) atoms in 3Fe(OH)3, and each oxygen atom has an atomic number of 8. So, there are a total of 9 x 8 = 72 oxygen atoms in 3Fe(OH)3.

There are 9 hydrogen (H) atoms in 3Fe(OH)3, and each hydrogen atom has an atomic number of 1. So, there are a total of 9 x 1 = 9 hydrogen atoms in 3Fe(OH)3.

Adding the number of iron, oxygen, and hydrogen atoms, we get 78 + 72 + 9 = 159 atoms in 3Fe(OH)3.