Drop down menu and product - thank you

[Xample]

Hi guys,

This is my first post here so I hope I will do it ok.

I have a problem that seems to be a little over my head...

I'm trying to make a table that looks like this:

X Y Z Q Rezult


I need X to be a drop down menu with 3 possibilities: A, B, C

Now if X is A the result looks like this:

Result=Y*1.5*Z*Q*20

if X is B the result looks like this:

Result=Y*1*Z*Q*10

if X is C the result looks like this:

Result=Y*0.5*Z*Q*30

I hope it's possible ...


PS. excuse my english