First of all, I spend Rs.20 to recharge my mobile I get Rs.30 as balance.Once again I spend Rs.15 to recharge my mobile,I received Rs.15 as the balance.By now I've spent Rs.35 and have received Rs.45 as balance.Further from remaining Rs.15,again I spend Rs.9 and receive Rs.6 as balance.Now with remaining Rs 6 again I recharge my mobile but don't receive any balance but 50 MB free internet data for 1 day.In all, I spend Rs.50 and my balance is Rs.51.