Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

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

Joseph buys three kinds of chocolates for 100 rupees. The first one is priced at 5 rupees, second one at 3 rupees and third one at 0.5 rupees.

If he bought 100 chocolates in total, how many pieces do you think he bought each chocolate?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

Can you find out the remainder when 3^300 is divided by 5?

You have two jars of chocolates labelled as P and Q. If you move one chocolate from P to Q, the number of chocolates on B will become twice the number of chocolates in A. If you move one chocolate from Q to P, the number of chocolates in both the jars will become equal.

Can you find out how many chocolates are there in P and Q respectively?

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 ()

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?