A toy is sold for Rs. 220. What was the cost, if the rate of profit was 10% of the cost?

A) Rs. 198

B) Rs. 200

C) Rs. 210

D) Rs. 240

 S.P = 220, Profit % = 10%
We Know the formula
Profit = (Selling Price-Cost Price)*100/Cost Price
Applying it 
10 = (220 – C.P)*100/C.P
10/100 = (220-C.P)/C.P
C.P/10 = 220 – C.P
CP+10 C.P = 2200
CP = 2200/11 = 200