A letter on the cabinet

This is a letter from someone who obviously likes tacos. Surprisingly, that person put a hidden message in it. If you get the first letter of each line, you get the two words "Behind Time". Then, look behind the monitor with the time on it, and you'll see some text on there. This will lead you to info for the worldmap.

Math on the wall

The math on the wall has symbols. Each symbol has a different amount of sides. A square has four sides, a triangle has three and a circle has one. If you replace the symbols with the amount of sides the figure has, you will get:

4 - 3 ÷ 3 + 1 = ?

This doesn't work from left to right. You will have to use the mathematical order of operations for this to work. This means:

4 - (3 ÷ 3) + 1 = ?

You will get 4 as answer. This is, as seen on the back of the monitor, the number for the worldmap.

The worldmap

By now you have all the information for the worldmap. The letter is E, and the number is 4. Combine those and you should get Australia as answer. You will need this with for the final answer.

Text upstairs and the wordlist on the wall

If you go upstairs, and look to the wall on the opposite side of the door, you can see the text which hints to the exit. There is a sentence which you can decrypt by using the wordlist on the wall, which are a lot of words! If you have decrypted every letter, you should get

Transform the country into numbers using the alphabet.

The alphabet on the wall and the final code

You now have everything to escape. The only thing left, is to transform the country into numbers using the alphabet, as you just discovered. So, using the "Alphabet in numbers" list on the wall, you can transform "Australia" into numbers. You will get:

12119201811291

​Put that into the keypad next to the door and you will escape!