A farmer bought 100 hens for ₹4000, sells 20 of them at a gain of 5%. At what gain % must he sell so as to gain 20% on the whole?
Toshiba bought 100 hens for Rs. 8000 and sold 20 of these at a gain of 5%. At what gain percent she must sell the remaining hens so as to gain 20% on the whole?