If 21x = 79x, what is the value of x?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

What have one eye but still cannot see?

There is a jar in which there are two types of candies.
20 blueberries and 16 strawberries. You perform the following steps:
1) You take out two candies.
2) If the two candies are of the same flavour, you add a blueberry one otherwise, you add the strawberry one.

You repeat these two steps till there is just one candy remaining in the jar. Which flavoured candy will be left?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

You bought me for dinner but never eat me. What am I?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

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

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.