A man dies of old age on his 25 birthday. How is this possible?

Divide 110 into two parts so that one will be 150 per cent of the other. What are the 2 numbers?

Solve the rebus riddle in the picture below.

There is a place where if I stand up straight, I will still be considered sideways.

What am I?

What has a bottom at the top?

Our product and our sum always give the same answer. Who are we?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

A swan sits at the center of a perfectly circular lake. At an edge of the lake stands a ravenous monster waiting to devour the swan. The monster can not enter the water, but it will run around the circumference of the lake to try to catch the swan as soon as it reaches the shore. The monster moves at 4 times the speed of the swan, and it will always move in the direction along the shore that brings it closer to the swan the quickest. Both the swan and the the monster can change directions in an instant.
The swan knows that if it can reach the lake's shore without the monster right on top of it, it can instantly escape into the surrounding forest.

How can the swan successfully escape?

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