A shopkeeper buys two articles for a total of Rs 1200. He sells the first at a profit of 25% and the second at a loss of 8%, and receives Rs 1335 in all. Find the cost price (in Rs) of the first article.

Let the cost prices be Rs $x$ and Rs $y.x+y=1200$ and $1.25x+0.92y=1335$. Substituting $y=1200-x:1.25x+1104-0.92x=1335$, so $0.33x=231$ and $x=700$, giving $y=500$. Check: 700 + 500 = 1200 and 875 + 460 = 1335. 500 is the second article's cost price; 875 is the first article's selling price, not its cost; 600 assumes the two articles cost the same.