If 21x = 79x, what is the value of x?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

There are two insects on a tile. Insect X is sitting on one side of the tile (point A) and Insect Y is sitting opposite on the other side of the tile (point B). Now both of them decide to change their position and thus X starts crawling to point B and Y starts crawling to point A. When they meet and pass each other in between, X takes 20 seconds to reach B and Y takes just 5 seconds to reach A.

Can you calculate the total time each of the insects took to change their positions?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?