A shopkeeper sells two articles, A and B. The ratio of the cost price of A and B is 4:5, respectively. The marked price of A is thrice the marked price of B. The selling price of A is Rs 840, which is Rs 840 more than the discount offered on it. What is the profit earned on B (in Rs)?
I: The cost price of A is Rs 700, and the profit earned on B is 20% of its cost price.
II: The selling price of A is Rs 665 more than the profit earned on B.

Correct option is D

Let the cost price of A and B be 4a and 5a respectively.
Let the marked price of A and B be 3b and b respectively.
Selling price of A = Rs 840
The selling price of A is Rs 840, which is Rs 840 more than the discount offered on it
So, discount offered is 0
3b – 0 = 840
3b = 840
b = 280
The marked price of A and B be Rs 840 and Rs 280 respectively.
Form I:
The cost price of A = Rs 700
The cost price of B = 700×5/4= Rs 875
The profit earned on B = 875×20/100= Rs 175
I is sufficient.
Form II:
The selling price of A = Rs 840
Profit earned on B = 840 – 665 = 175 Rs
II is sufficient.

Exam Hall Method: