the answer is B can you please explain how you get to the answer please?

ABLES 171 In the statement of financial position at 31 December 20X5, Boris reported net receivables of $12,000. During 20X6 he made sales on credit of $125,000 and received cash from credit customers amounting to $115,500. At 31 December 20X6, Boris decided to write off debts of $7,100 and increase the specific allowance for receivables by $950 to $2,100. What was the net receivables figure reported in the statement of financial position at 31 December 20X6? A $12,300 B $13,450 $14,400 $15,550 D