Step 1: Calculate Gross Value Added (GVA) of Firm Y.
$GVA_{Y} = \text{Value of Output of Y} - \text{Intermediate Consumption of Y}$
Intermediate Consumption of Y = Purchases made by Y from X = ₹ 300 crore.
$GVA_{Y} = 1,400 - 300 = ₹ 1,100 \text{ crore.}$
Step 2: Find the Value of Output for Firm X.
Given that $GVA_{X} = GVA_{Y}$, we have $GVA_{X} = ₹ 1,100$ crore.
$GVA_{X} = \text{Value of Output of X} - \text{Intermediate Consumption of X}$
Intermediate Consumption of X = Purchases made by X from Y = ₹ 400 crore.
$1,100 = \text{Value of Output of X} - 400$
$\text{Value of Output of X} = 1,100 + 400 = ₹ 1,500 \text{ crore.}$
Step 3: Determine Domestic Sales of Firm X.
$\text{Value of Output of X} = \text{Total Sales} + \text{Addition to Stock}$
$1,500 = \text{Total Sales} + 100 \implies \text{Total Sales} = ₹ 1,400 \text{ crore.}$
$\text{Total Sales} = \text{Domestic Sales} + \text{Exports}$
$1,400 = \text{Domestic Sales} + 200 \implies \text{Domestic Sales} = ₹ 1,200 \text{ crore.}$