What does this mathematical rebus means ?

The two towns are exactly 100 km apart. John leaves City A driving at 30 km/hr and Jacob leaves City B half an hour later driving at 60 km/hr. Who will be closer to City A when they meet?

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

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

Which part of London exists in France as well ?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

By using 'because' continuously three times, can you make an English statement ?

The captain of a ship was telling this interesting story: "We travelled the sea far and wide. At one time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly." How can that be possible?