Accrual and prepayments

At 31 dec 2003, tony had accrued 240 in respect to heat and light for the quater ending 31dec 2003. in jan 2004 he discovered that bill was under accrued by 10 the bills for the next quater were as follows: amt related to data paid 260 q.e 31mar 2004 15 apri 2004 220 q.e 30 june 2004 17 july 2004 210 q,e 30 sep 2004 14 oct 2004 230 q.e 31 dec 2004 19 jan 2005 tony always accrues for expenses based on the last bill what charge to p&l in respect to light and heat for the 15month accounting period ended 31 mar 2005? i managed to get 250(240+10) and 950(260+220+210+230) on the debit side and 240 on credit side the debit side also shows additional 230? how to calculate this figure?