Paper 1 February/March 2016 Accounting (9706/12) A Level

Brian had a service business which held no inventory. His current assets and current liabilities at 1 April were as follows.
On that date he set off a sales ledger balance, $\$ 600$, against a purchases ledger balance and then created a provision for doubtful debts of 5%.
What was the value of his working capital after these adjustments?