The answer is 11910 can you explain why b/d and c/d are both on the right side of the ledger please?

5.2 The following information relates to Eva Co's sales tax for the month of March 20X3: $ Sales (including sales tax) 109,250 Purchases (net of sales tax) 64,000 Sales tax is charged at a flat rate of 15%. Eva Co's sales tax account showed an opening credit balance of $4,540 at the beginning of the month and a closing debit balance of $2,720 at the end of the month. What was the total sales tax paid to regulatory authorities during the month of March 20X3