Okay, let's break this down step-by-step:
In the beginning of BS 2077, Dolma deposited B? 120,000 in her account.
The interest rate is 9% per annum.
So in the first year (BS 2077), she earned 9% of 120,000 = B? 10,800 in interest.
Her principal amount increased to 120,000 + 10,800 = B? 130,800
In BS 2078, she earned 9% of 130,800 = B? 11,772 in interest.
Her principal now was 130,800 + 11,772 = B? 142,572
In BS 2079, she earned 9% of 142,572 = B? 12,781 in interest.
Her principal now was 142,572 + 12,781 = B? 155,353
In the beginning of BS 2080, her total balance was B? 155,353.
She paid 6% of her interest as income tax.
9% of 155,353 is 13,991.
6% of 13,991 is 839.
So her total interest received in BS 2080 after paying tax was 13,991 - 839 = B? 13,152.
Her total amount received in BS 2080 was:
Principal (155,353) + Interest (13,152) = B? 168,505
So the total amount Dolma received in the beginning of BS 2080 was B? 168,505
Let me know if you have any other questions!