IF ALL NITROGEN ATOMS FROM .1 MOLE nO2 AND .2 MOLE N2O4 ARE REMOVED THEN HOW2 MANY MOLES OF N2 CAN BE PREPARED FROM IT?

Please don't post in all caps. It makes the question difficult to read.

0.1 mol NO2 and 0.2 mol N2O4.

So you have 0.1 mol N from NO2 = 0.05 mol N2 from NO2.
You have 2*0.2 = 0.4 mol N2 from N2O4.
Total is 0.4 + 0.05 = ?