A shopkeeper defrauds both the dealer and the customer by measuring weights incorrectly. The shopkeeper cheats 20% while purchasing and 40%…

Let the rate be Rs. 100/Kg

While buying he gets 1.2 Kg at Rs. 100

∴ Cost price of 3.6 Kg = 3 × 100 = Rs. 300

He sells his goods at a loss of $(16\frac{2}{3}{\rm{\% }})$ = 1/6

And while selling he sells 0.6 Kg at 100 × (5/6)

⇒ 3.6 Kg at Rs. 500

Now,

Cost price of 3.6 Kg = Rs. 300

Selling price of 3.6 Kg = Rs. 500

Profit % = $(\left( {\frac{{200}}{{300}}} \right))$ × 100 = 66.67%