Quantitative Aptitude - Arithmetic Ability Questions

If 1/2 is added to a number and the sum is multipled by 3, the result is 21. Then the number is

If Cosec θ = 17/8, then Cot θ = ?

A merchant marks the price of his articles 30% above the cost price. He gives some discount on it and earns a profit of 13.75%. What is the discount percentage?

A boy running at 10/9 th of his actual speed covers 39 km in 2 hours 20 minutes and 24 seconds. Find the actual speed of the boy (approx.)

If x+y+z = 1, 1/x + 1/y + 1/z = 1 and xyz = -1, then x3+y3+z3 is equal to

What is the effective discount on two successive discounts of 20% and 25%?

Two numbers are 35% and 50% lesser than a third number. By how much percent is the second number to be enhanced to make it equal to the first number? 

The ratio of present ages of R and S is 6:7. Before 12 years the ratio of their ages was 9:11. What is R's present age (in years)?