Answer: (4) 71%

Solution;

Let’s say cost for 100gm is 100 Rupees

He adds 20% impurity. So now total qty is 120gms.

Now he cheats the consumer by 30%. It means he recovers 100 rupees by selling 70gms.

Hence his profit is remaining 50 gms over 70gms

hence profit% = 50/70*100% = 71%