FAAccrued Expenses (Kaplan p438, Q30)

Cant figure out how the income statement charge is calculated on this one. Trying to imagine how it can be go. Even looking at the solution cant understand. I'd love to be able to draw a t-account but I'll explain as best I can. At 31 December Tony has accrued 240$ in respect of light and heat for the quarter ending 31 December 2003. In Janurary 2004 he dicovered that he under accrued by 10$. The bills for the next four quarter were as follows: (q.e. = quarter ended? Amount 260 Q.E. 31Marc2004 Paid 15 April 2004 Amount 220 Q.E. 30June2004 Paid 17 July 2004 Amount 210 Q.E. 30Sept2004 Paid 14Octr2004 Amount 230 Q.E. 31Decb2004 Paid 19Jany2005 Tony always accrues for expenses based on the last bill. What is the charge to the income statement in respect of light&heat for the 15month period ended 31March2005? The answer according to the book is: 1,160. I understand to subtract the 10$ for under accrual and use 230 for the accrual heading into the next period. What i dont understand in the solution is why they have the opening accrual of 240$ on both sides of the T-Account? The debit sides reads: 250(240+10)+260+220+210+230+230(c/f). The credit side 240(b/f). I am really struggling to see why this was done? Anyone have any idea? Many thanks.