Revenue - Depreciation

Hi. This question is from Kaplan ST chapter 11 TYU 8 Please help me understand how the depreciation is calculated for Plant & Machinery. Thank you so much! Merryview specialises in long-term contracts. In each contract Merryview is entitled to receive payments reflecting the progress of the work, so revenue should be recognised over time. One of its contracts, with Better Homes, is to build a complex of luxury flats. The price agreed for the contract is $40 million and its scheduled date of completion is 31 December 20X2. Details of the contract to 31 March 20X1 are: Commencement date 1 July 20X0 Contract costs: $000 Architects’ and surveyors’ fees 500 Materials 2,800 Direct labour costs 3,500 Overheads are apportioned at 40% of direct labour costs Estimated cost to complete (excluding depreciation – see below) 14,800 Plant and machinery used exclusively on the contract cost $3,600,000 on 1 July 20X0. At the end of the contract it is expected to be transferred to a different contract at a value of $600,000. Depreciation is to be based on a time-apportioned basis. Better Homes made a progress payment of $12,800,000 to Merryview on 31 March 20X1.