A business man buys a pen for Tk. 25.00. He spends Tk.15.00 to have it restored to good condition and then sells the same for Tk. 50.00. The percentage of profit on his total investment is

If a > b > c then which of the followings must be true?

How many pounds of pure salt must be added to 30 pounds of a 2% solution of salt and water to increase it to a 10% solution?

What number must be added to (x² - 18x) to make the result a perfect square?

An investor invests 30%, 40%, 20% and 10% of his total investable amount in four different shares of stock giving returns of 15%, 20%, 12% and 10% respectively. What is the average rate of his returns?