A and B start a business jointly. A invests Rs. 16,000 for 8 months and B remains in  the business for 4 months, Out of total profit, B claims – of the profit. How much money was contributed by B?

Let the total profit be Rs. x. Then, B = 2x/7 and A = (x – 2x /7) =  5x / 7.
So, A : B = 5x/7 : 2x/7 = 5 : 2.
Let B s capital be Rs. y. Then, (16000 * 8) / ( y * 4) = 5/2  <=> (16000 * 8 * 2) / (5 * 4) = 12800.