Sonia bought washing machine 10000and paid 2000 and rest in installments of rs 500 at the rare 10℅ find the total amount paid
Too many unknowns here.
Is this compound interest or simple interest?
Are the instalment payments made monthly or ?
Since it will take more than a year to pay it with monthly instalments, I will assume compound interest.
i = .10/12 = .00833...
then
500(1 - 1.008333...^-n)/.008333... = 8000
1 - 1.008333..^-n = .13333...
1.008333..^-n = .8666....
take logs of both sides:
-n log 1.008333.. = log .8666...
-n = -17.24..
n = 17.24
She will need 17 full payments of 500 plus a small partial payment at month 18