To calculate the sales figure, we need to determine the amount that was received from the debtors. We can do this by subtracting the total debtors b/d 31/12/99 from the total debtors c/d 31/12/00 and adding the cheques received from debtors.
((15,000 - 25,000) + 255,000) = 245,000
So, the sales figure is ₦245,000.