In Part (a), depreciation is directly credited to the Machinery Account, reducing the asset's book value yearly. However, based on the context of similar textbook problems (like Ganga Ltd.), the Machinery Account is often maintained at cost while a separate Provision for Depreciation Account handles the accumulated depreciation. Part (a) usually implies crediting the asset account directly unless 'Provision' is specified, but the standard exam practice for 'Machine Account and Depreciation Account' often mirrors the 'Provision' method by keeping the asset at cost to track historical cost, or deducts depreciation to show net value. Given the explicit request for 'Provision for Depreciation' in part (b), part (a) typically credits depreciation directly to the Asset account (Machinery A/c) to show the written-down value. However, in the provided text solutions for similar problems (Ganga Ltd.), the Machinery Account balance remains high (historical cost), suggesting the 'Provision' method is the primary focus of the chapter. To distinguish (a) from (b), in (a) the Depreciation A/c is debited and Machinery A/c is credited. In (b), the Depreciation A/c is debited and Provision for Depreciation A/c is credited. Note: The solution presented maintains the Machinery Account at original cost for clarity, as the written down value is typically derived via the Provision account in these contexts.