F4 mole concept (20點!! 急!!)

Let m be the molar mass of X.
Number of atoms containing in 1 mole of XO2
=1*(1+2)*L, where L is the Avogadro constant {since 1 mole of XO2 contains 1 mole of X and 2 moles of O)
=3L
Number of atoms containing in 60g of XO3
=[60/(m+16.0*3)]*(1+3)*L {since 1 mole of XO3 contains 1 mole of X and 3 moles of O)
=(240L)/(m+48)
Hence 3L = (240L)/(m+48)
m = 32 g/mol
Therefore molar mass of XO2
=32+16.0*2
=64.0 g/mol

Supposing m g mol^-1 be the molar mass of XO2
And L be the Avogadro's Constant(6.02x10^23)
No. of atoms in XO2 = 3L because there are 3 atoms(1X atom and 2O atoms) in the XO2 molecule
And consider the molecule XO3
no. of atoms in XO3 = [60/(m+16.0)](4L) => 4L -> 1X atom and 3O atoms
= 240L/(m+16.0)

3L = 240L / (m+16.0) => same no. of atoms
m + 16.0 = 80
m = 64.0 g mol^-1