What does this mathematical rebus means ?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

Before reading ahead, you must know the fact that only one of the people here is telling the truth.

A says that B is lying.
B says that C is lying.
C says both A and B are lying.

Can you find out who is speaking the truth?

How many minutes are there in Feb 2017?

Note: The shortest answer is the correct answer.

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?