If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

What does this rebus puzzle means ?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

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

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?