Dove Ltd operates a factory that contains a large number of machines designed to produce knitted garments. These machines are generally depreciated at 10% p.a. on a straight-line basis. In general, machines are estimated to have a residual value on disposal of 10% of cost. At 1 July 2017, Dove Ltd had a total of 64 machines, and the statement of financial position showed a total cost of $386,000 and accumulated depreciation of $120,000. During 201718, the following transactions occurred:

1.	On 1 September 2017, a new machine was acquired for $14,000. This machine replaced two other machines. One of the two replaced machines was acquired on 1 July 2014 for $7,500. It was traded in on the new machine, with Dove Ltd making a cash payment of $8,100 on the new machine. The second replaced machine had cost $8,300 on 1 April 2015 and was sold for $6,700.
2.	On 1 January 2018, a machine that had cost $3,700 on 1 July 2008 was retired from use and sold for scrap for $460.
3.	On 1 January 2018, a machine that had been acquired on 1 January 2015 for $6,400 was repaired because its motor had been damaged from overheating. The motor was replaced at a cost of $4,400. It was expected that this would increase the life of the machine by an extra 2 years.
4.	On 1 April 2018, Dove Ltd fitted a new form of arm to a machine used for putting special designs onto garments. The arm cost $1,100. The machine had been acquired on 1 April 2015 for $9,200. The arm can be used on a number of other machines when required and has a 15-year life. It will not be sold when any particular machine is retired, but retained for use on other machines.

(a)