A shopkeeper sells transistors at 15% above its cost price. If he had bought it at 5% more than what he paid for it and sold it for ₹ 6 more, he would have gained 10%. The cost price of the transistor is?

Let cost price of transistor = ₹ N
According to the question,
CP of transistor = (N x 105)/100
And SP of transistor = (115 x N)/100 + 6
∴ Profit percentage = (SP - CP)/CP x 100
⇒ 10 = [[(115N/100) + 6 - (105N/100)] / (105N/100)] x 100
⇒ 10 = [(10N + 600) x 100]/ 105N
⇒ 105N = 100N + 6000
⇒ 5N = 6000
⇒ N= ₹ 1200