What does this mathematical rebus means ?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

You need to remove two matchsticks to make the below equation true. Can you do it ?

Which five letter word can be added at the end of below word to form a
valid word?

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The host of a game show offers the guest a choice of three doors. Behind one is an expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

What number do you get when you multiply all of the numbers on a telephone's number pad?

Which of the below owl is odd one out?

It is always ahead of me yet I can never see it. What is it?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

In particular commonwealth games, a female participant won silver and gold medals for a single event.

How can this be possible?