Find the missing letter in the last circle logically in the given below picture.

Name a key which is hardest to turn.

It is a six-letter word.
The first four letters are me.
The second and last letters are the same.
The fourth second and last letter is payment.

Who is it?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

Can you count the number of quadrilaterals in the picture below?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

Find the next number in the sequence

5 12 24 36 ?

Can you find a rabbit in the given picture?