A sold a watch to B at a profit of 20%. B sold it to C

Solution

Let A purchased at Rs. 100 ⇒ A sold to B at a 20% profit = 100 × (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 × (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 × (90/100) ⇒ C sold to D at a 10% loss = 140.4 From (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 ∴ D bought it for Rs. 702