Doubt from gaseous state

Screenshot_20191104-121849 question 11
my doubt is if we find volume of 1 balloon and just divide by given volume why we cant get the ans..whereas we are getting ans by dividing moles of gases..if we apply i.g.e then what should be pressure taken 20??
@Shiva_1 sir, @Akash_2 sir , @Mayank_2019_1 sir..

@azimuddin_2019 sir @arush_2019 bro please give your point of view..

Take the pressure in ballon as 1atm to make an equilibrium with atmosphere.

not getting what you want to say sorry..