Step 1: Calculation of Purchases of Plant & Machinery
\[
\text{Closing Balance} = \text{Opening Balance} + \text{Purchases} - \text{WDV of Asset Sold} - \text{Depreciation}
\]
\[
17,20,000 = 14,40,000 + \text{Purchases} - 2,20,000 - 1,70,000
\]
\[
\text{Purchases} = 17,20,000 - 14,40,000 + 2,20,000 + 1,70,000
\]
\[
\text{Purchases} = ₹6,70,000
\]
Step 2: Cash Flow from Investing Activities
\[
\text{Cash Inflow from Sale of Plant} = ₹2,50,000
\]
\[
\text{Cash Outflow for Purchase of Plant} = ₹6,70,000
\]
\[
\text{Net Cash Flow from Investing Activities} = 2,50,000 - 6,70,000 = (-₹4,20,000)
\]