Answer:
Cost of the pen = Rs.100
Step-by-step explanation:
Let the marked price = x
When the shopkeeper is selling for x, his gain = Rs. 20
Cost price = Marked price - Gain = x - 20 --------(I)
After discount:
Discount = 10%
Marked price after discount = (100 - 10)% of x = 90% of x
= 0.9 * x = 0.9x
When the shopkeeper is selling for 0.9x, his gain = Rs.8
Cost price = Marked price - gain = 0.9x - 8 -------(II)
From (I) and (II)
x - 20 = 0.9x - 8
x = 0.9x - 8 + 20
x = 0.9x + 12
x - 0.9x = 12
0.1x = 12
x = 12/0.1
x = 120
Marked price of pen = Rs.120
Cost price = 120 - 20
Cost price = Rs. 100
