If A gives B ₹4, B will have twice as much as A. If B gives A ₹15, A will have 10 times as much as B. How much did A have originally?

Explanation

Let A = x and B = y. If A gives B ₹4, then y + 4 = 2(x - 4), so 2x - y = 12. If B gives A ₹15, then x + 15 = 10(y - 15), so -x + 10y = 165. Solving gives x = 15 and y = 18. Therefore, A originally had ₹15.