Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

Three brothers Jacob, John, and James live in Mexico City. The product of the ages of these brothers is 175. Jacob and John are twins. How old is James?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

What does this mathematical rebus means ?

I am an odd number. Take away a letter and I become even. What number am I?

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

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

There is a number which when you multiply by 3 and subtract 2 from the result, then the resulting number is the reverse of the actual number.

What is the smallest number that stands true on the statement?