Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

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

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

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

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

I throw two dice simultaneously.

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

A man died and leaves Rs.10,000 in his will. There are 6 beneficiaries- his 3 sons and their wives. The 3 wives receive Rs.3960 of which Priyanka gets Rs.100 more than Tanu and Neha gets Rs.100 more than Priyanka.
Pramod gets twice as much as his wife, Tushar gets the same as his wife, and Prashant gets 50% more than his wife.

Who is married to whom?