Accruals and Prepayment

A company’s telephone bill consists of two elements. One is a quarterly rental charge, payable in advance; the other is a quarterly charge for calls made, payable in arrears. At 1 April 20X9, the previous bill dated 1 March 20X9 had included line rental of $90. Estimated call charges during March 20X9 were $80.
During the following 12 months, bills totalling $2,145 were received on 1 June, 1 September,
1 December 20X9 and 1 March 20Y0, each containing rental of $90 as well as call charges. Estimated call charges for March 20Y0 were $120.
What is the amount to be charged to the statement of profit or loss for the year ended 31 March 20Y0?

I needed help with the calculation. Thanks in advance!