Find profit or loss on disposal

Sweeto maintains a fleet of company cars and depreciates all vehicles on a straight-line basis over a period of three years from the month of acquisition. During 2012 the company disposed of the following vehicles:

I. A Volvo which had originally cost $32,000 on 1 April 2009 was sold on 31 July 2012 for $7,000
I. An Audi which had originally cost $40,000 on 1 September 2010 was sold on 30 November 2012 for
$18,000
What figure for profit or loss on disposal of non-current assets should appear in the company’s statement of
profit or loss for the year ended 31 December 2012?

Sir how do we get the dep amount ?