Correct Answer - Option 4 : Rs. 800
Given:
P sells an article @ gain 25%
Q sells same article @ loss 10%
R pays = Rs.900
Calculation:
Let assume that cost price to P = Rs. x
Cost price to Q = Rs. 125x/100
Cost price to R = Rs. (125x/100) × (90/100)
R pays = Rs. 900
According to question
x × (125/100) × (90/100) = 900
⇒ x = (900 × 100 × 100) / (125 × 90)
⇒ x = Rs. 800
∴ Cost to P is Rs. 800.