A fruiterer bought some longans. 2/5 kg of the longans were rotten and he threw them away. Then he sold 1/5 Of the remaining longans and had 16 kg of longans left. How many kilograms of longans did the fruit seller buy?

Answer 1

Let X be the number of kg of longans bought.
The number of rotten longans is X * 2/5 = X/5.
Thus, the number of longans left is X - X/5 = 4X/5.
The number of longans sold is 4X/5 * 1/5 = 4X/25.
So the number of longans left is 4X/5 - 4X/25 = 16 kg.
Thus, 4X/25 = 16
Thus, X = 16 * 25/4 = <<16*25/4=100>>100 kg. Answer: \boxed{100}.