Final answer:
The correct answer is option (c) Rs 100. To solve the problem, let's denote the marked price as MP. When the pen is sold at a 15% discount, the selling price is 0.85MP and there is a gain of Rs 10.
Step-by-step explanation:
Conversely, when the pen is sold at a 25% discount, the selling price is 0.75MP and there is a loss of Rs 2. We can set up two equations based on the information provided:
- 0.85MP - Cost Price (CP) = Rs 10 (gain)
- 0.75MP - CP = -Rs 2 (loss)
Solving these two equations, we first express CP in terms of MP using the first equation:
CP = 0.85MP - 10
Then we substitute CP from the first equation into the second:
0.75MP - (0.85MP - 10) = -2
This simplifies to:
0.75MP - 0.85MP + 10 = -2
-0.10MP = -12
MP = Rs 120
But upon closer inspection, it appears we have made an error in calculation. Let's try once more to correctly solve for MP:
0.75MP - (0.85MP - 10) = -2
-0.10MP + 10 = -2
MP = 120
Thus, even with the recalculation, we can see that the marked price ends up being Rs 120.