A trader cheats both his supplier and customer by using false weights.while buying from his supplier,he takes 10%more than the indicated weight.when he sells to his customer,he gives the customer a weight such that if 10% of that is added to the weight,the weight claimed by the trader is obtained.if he charges the c.p of the weight that he claims,find his profit per.?pl. provide sol.

1) 20%
2) 21%
3) 21 1/3%
4) 22 2/9%