Formula field based on other two formula fields

Formula field based on other two formula fields

Hi

I have some custom fields on Account like this:
€ field
formula field1: € field*21/100
formula field2: € field*7/100

I need a third formula field3 like this: € field+formula field1 - formula field2.

I can not create this formula because in the wizard the formula fields are not appearing.

Any idea?

Thanks in advance.