A fruit-seller buys some oranges and by selling 40% of them he realises the cost price of all the oranges. As the oranges being to grow over-ripe, he reduces the price and sells 80% of the remaining oranges at half the previous rate of profit. The rest of the oranges being rotten are thrown away. The overall percentage of profit is

Let us assume that the fruit seller buys 100 oranges for Rs. 100
He sells 40 oranges for Rs. 100
Profit obtained = 100 - 40 = Rs. 60
% Profit = $$\frac{60}{40} \times 100 = 150$$%
Now, he sells 80% of the remaining oranges at half the profit
i.e., he sells 48 oranges at 75% profit.
Selling Price of 48 oranges = 48 + 75% of 48 = Rs. 84
Rest of them are thrown away.
Total SP = 100 + 84 = 184
Profit = 184 - 100 = 84
% Profit = 84%