I have teeth but i don't bite. Who Am I ?

Count the number of triangles in the picture below:

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

I am sure no one can have two things for dinner. what are they?

What is the fastest way to double your money?

How can you take 2 from 5 and leave 4?

In the figure that has been attached to this question, each digit represents a digit. The similar letters carry the same integer value. Can you expose the original digits?

Take one out and scratch my head, I am now black but once was red. What am I?

If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?