Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A man had five children. He had $100 with him to give to his children. He decided to start with the youngest child and then give $2 more than each younger child to his next elder child.

For example, if he gives $x to the youngest child, he will give $(x+2) to the next one, $[(x+2) + 2] to the next one and so on.

Can you find out how much did the youngest one receive?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

Replace the 'X' with any mathematical symbol to make the expression equal to 111.

18 X 12 X 2 X 3 = 111

You have $100 with you and you have to buy 100 balls with it. 100 is the exact figure and you can't go below or above the numbers and you have to use the entire $100. If there is no kind of tax applied how many of each of the following balls will you be able to buy:

Green Balls costing $6
Yellow Balls costing $3
Black Balls costing $0.10

Now, how many of each must you buy to fulfil the condition given?