Correcting Journal Entries for Errors

The following are independent errors:

a.	In January 2016, repair costs of $9,000 were debited to the Machinery account. At the beginning of 2016, the book value of the machinery was $100,000. No residual value is expected, the remaining estimated life is 10 years, and straight-line depreciation is used.
b.	All purchases of materials for construction contracts still in progress have been immediately expensed. It is discovered that the use of these materials was $10,000 during 2015 and $12,000 during 2016.
c.	Depreciation on manufacturing equipment has been excluded from manufacturing costs and treated as a period expense. During 2016, $40,000 of depreciation was accounted for in that manner. Production was 15,000 units during 2016, of which 3,000 remained in inventory at the end of the year. Assume there was no inventory at the beginning of 2016.

Required:

Prepare journal entries for the preceding errors discovered during 2017. Ignore income taxes.