Counting principles, three letter sequence w/o repeated letters, containing e or f

How many three-letter sequences without repeated letters can be made using a,b,c,d,e,f in which either e or f (or both) is used?

I looked at the total sequences posible with all letters:

6*5*4=120 this is w/o replacement

The I looked at the amount of sequences without e or f:

4*3*2=24

Then I substract the amount of sequences without e or f from the total amount of possible sequences:

**(6*5*4)-(4*3*2)=96 amount of sequences with e or f**

But now I want to find the amount of sequences with e or f directly.

Here I have a problem because it is e or f.

If I would look for "without repetition and containing the letter g," I would do

g _ _ 5 * 4 = 20

NOg g _ 5 * 4 = 20

NOg NOg g 5 * 4 = 20 and then add it up 20 + 20 + 20 = 60

How can I do this with g or f?