If u have 200 courses to choose from and can only choose 4 how many choices do u have. is it 200:4?

No, it is not 200/4. Because in the question, it says you have 4 choices.

Basically the question means

how many ways are there to choose 4 classes if you have 200 classes to choose from?

so permutations (combinations is if you can repeat choices, but obviously you won't take the same class 4 times)

slot system (simple way to explain permutations)

so you have 4 slots to fill and you have 200 choices

1st slot: 200 choies

2nd slot: 199 choices (1 less choice)

3rd slot: 198 choices (1 less choice)

4th slot: 197 choices (1 less choice)

to find how many ways, we do,

200*199*198*197 = 1,552,438,800 choices

no it is not 200/4