A man earns a profit of 60% when he sells an article at 4/3 of the original selling price. Find the percent profit he makes at original price.

Arun purchased 30 kg. of rice at the rate of Rs. 17.50 per kg. and another Rs. 30 kg. at a certain rate. He mixed the two and sold the entire quantity at the rate Rs. 18.60 per kg. and made 20% overall profit. At what price per kg. did he pruchase the lot of another 30 kg. rice?

Three science classes A, B and C take a Science test. The average score of class A is 83. The average score of class B is 76. The average score of class C is 85. The average score of class A and B is 79 and average score of class B and C is 81. Then the average score of classes A, B and C is

A boat goes from A to B in upstream and come back from B to A downstream taking a total time of 3.5 hours. If the speed of boat in still water is 7 km/hr and the speed of stream is 5 km/hr. Find the distance between A and B. 

Simplify the following equation
$$ {\sqrt{(1-sin^{2}θ) ÷{(1-cos^{2}θ)}}}$$

Aman and Ajay can build a wall in 9 days and 12 days respectively. In how many days can they finish the work if they work together?

Simple interest on an amount is Rs. 24 and true discount on the same is Rs. 20. The principal amount is

If the profit on selling an article for Rs. 579 is the same as the loss on selling it for Rs. 337, then find the profit percent if its selling price is Rs. 687.