Lets see how can I sort this out:
We may say that discounts offered are 5% within 10 days, 4% within 30 days and no discount after that. Since bill was paid on June 4 it was over 10 days but under 30 so a discount of 4% will apply to principle balance .
In this case total amount paid will be like this: 1000+16000×0.96=16360
