A sole trader's trial balance shows: Sales R450 000, Cost of Sales R270 000, Operating expenses R100 000. If drawings are R30 000, calculate closing capital when opening capital was R200 000.

Net Profit is calculated as Sales minus Cost of Sales minus Operating Expenses.

$$\text{Net Profit} = \text{Sales} - \text{Cost of Sales} - \text{Operating Expenses}$$ $$\text{Net Profit} = \text{R450 000} - \text{R270 000} - \text{R100 000}$$ $$\text{Net Profit} = \text{R180 000} - \text{R100 000}$$ $$\text{Net Profit} = \text{R80 000}$$

Closing Capital is calculated as Opening Capital plus Net Profit minus Drawings.

$$\text{Closing Capital} = \text{Opening Capital} + \text{Net Profit} - \text{Drawings}$$ $$\text{Closing Capital} = \text{R200 000} + \text{R80 000} - \text{R30 000}$$ $$\text{Closing Capital} = \text{R280 000} - \text{R30 000}$$ $$\text{Closing Capital} = \text{R250 000}$$

The calculated closing capital is R250 000, which matches option A.

The final answer is $\text{A. R250 000}$.