There are six entrances to a haunted house. if you do not exit the same way you entered, how many different ways can you enter and exit the house? a.) 20b.) 25c.) 30d.) 36

There are 6 ways to enter and 5 ways to leave once you pick a specific door to enter (in which you cannot re-use to exit). So overall there are 6*5 = 30 different permutations to pick from

Choice C) 30

Note: you can use the nPr formula with n = 6 and r = 2 to get the same answer
Alternatively, you can use a probability tree to map out all the possibilities though such a tree with 30 branches may take a while to draw out 

Ummm ok. for informing us