What does this Rebus Picture mean?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

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

On a bright sunny day, two fathers took their son fishing in the lake. Each man and son were able to catch one fish. When they returned to their camp, there were only three fishes in the basket. What happened?

PS: None of the fish were eaten, lost, or thrown back.

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

John is selling fruits.
He sells grapes at $30, Dates $25, and a Wolfberry $45.
At what price does he sell fig?

PS: Logical Thinking

What begins with T, ends with T, and has T in it?

I can be made.
I can be cracked.
I can be told.
I can be played.

Who am I?