A sold a watch to B at a profit of 20%. B sold it to C at 30% profit. C sold it to D at 10% loss. If B's profit is Rs. 80 more than that of A, then D bought it for:

Solution (By Examveda Team)

Let A purchased at Rs. 100
⇒ A sold to B at a 20% profit = 100 × $$\frac{{120}}{{100}}$$
⇒ A sold to B at a 20% profit = 120
⇒ A's profit = 120 - 100
⇒ A's profit = 20 - - - - - - - - (1)
⇒ B sold to C at a 30% profit = 120 × $$\frac{{130}}{{100}}$$
⇒ B sold to C at 30% profit = 156
⇒ B's profit = 156 - 120
⇒ B's profit = 36 - - - - - - - - (2)
⇒ C sold to D at a 10% loss = 156 × $$\frac{{90}}{{100}}$$
⇒ C sold to D at a 10% loss = 140.4
From equation (1) and (2)
The difference in profit of B and A
⇒ B's profit - A's profit = 36 - 20
⇒ B's profit - A's profit = 16
So. 16x = 80
⇒ x = 5
∴ D bought it for 140.4 × 5 = Rs. 702.