The sum of the digits of a two digit number is 15. When 9 is subtracted from the given number then its digits interchanged. What will be the required original number?

The number of mainas and parrots in an aviary is in the ratio of (4x + 5) : 4x. If 25 mainas and 10 parrots are added to the aviary, then, the ratio would change to 5: 3. How many mainas are there in the aviary at initial?

An observer who is 1.62-meter-tall is 45 meters away form a pole. The angle of elevation of the top of the pole from his eyes is 30°. The height ( in meter) of the pole is closet to:

When (6767 +67) is divided by 68, the remainder is-

A sum of money becomes two times of itself in 8 years at simple interest, and it becomes four times of itself in 2 years at compound interest, when interest is compounded annually. Find the ratio of the rate of simple interest to the rate of compound interest offered per year.

A man can row downstream at a speed of 15 km/h and upstream at 11 km/h. Find his speed in still water and the speed of the current, respectively. [Give both your answers in km/h]

Two numbers, of which the first number is 200% of the second number. If the sum of the squares of the first number and the cube of the second number is 5 times the product of both numbers, find the difference between the two numbers?

In a division sum, the divisor is ten times the quotient and five times the remainder. If the remainder is 46, find the dividend.