JNU SSS 2017 Question 44: National income accounting

The production sector of a closed economy consists of only two firms, $A$ and $B$, which produce products $x$ and $y$ respectively. $x$ is exclusively an intermediate good and the only intermediate used in the production of both $x$ and $y$, while $y$ is the final good. The unit prices of $x$ and $y$ are ₹ 5 and ₹ 10 respectively. The stocks of unused or unsold $x$ and $y$ held by the two firms at the beginning and at the end of the year are given in the table below :

	Stocks at Year Beginning (no. of units) - $x$	Stocks at Year Beginning (no. of units) - $y$	Stocks at Year End (no. of units) - $x$	Stocks at Year End (no. of units) - $y$
Firm $A$	20	0	25	0
Firm $B$	10	10	20	20

If firm $B$'s sales in the year are ₹ 10,000, determine the economy's GDP in that year.