Using Only Five 5's and any mathematical operator make sum as 37

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

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

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

First, think of the colour of clouds. Next think the colour of snow. Last, think of the colour of the moon. Now, what do cows drink?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?

A worker is to perform work for you for seven straight days. In return for his work, you will pay him 1/7th of a bar of gold per day. The worker requires a daily payment of 1/7th of the bar of gold. What and where are the fewest number of cuts to the bar of gold that will allow you to pay him 1/7th each day?