Payables ledger control account

Hello. May you answer my question please? In the answer (b) $2,420 is deducting from the payables ledger control account (as debit). Why is it deducting? It is just written that $2,420 has been offset wrongly in the payables ledger (not nominal ledger) as $3,650. There is no information that it has not been offset in the control account. Thanks At 1 April 20X9, the payables ledger control account showed a balance of $142,320. At the end of April the following totals are extracted from the subsidiary books for April: Purchases day book: $183,800 Returns outwards day book: $27,490 Returns inwards day book: 13,240 Payments to payables, after deducting $1,430 cash discount: 196,360 It is also discovered that: (a) the purchase day book figure is net of sales tax at 17.5%; the other figures all include sales tax. (b) a customer’s balance of $2,420 has been offset against his balance of $3,650 in the payables ledger. (c) a supplier’s account in the payables ledger, with a debit balance of $800, has been included on the list of payables as a credit balance. What is the corrected balance on the payables ledger control account?