calculate the number of moles in 6o gm NaOH?

Suppose that it is "60 gm NaOH".

Molar mass of NaOH = (23 + 16 + 1) g/mol = 40 g/mol
No. of moles of NaOH = (60 gm) / (40 gm/mol) = 1.5 mol