What does this rebus puzzle means ?

Solve below rebus puzzle?

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognises the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14. Where has the other $1 gone from the original $15?

Why is it against the law for a man living in Delhi to be buried in Mumbai?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

What jumps when it walks and sits when it stands?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?