minute vs minutes

[Daniellll]

do we say:
- I have a 5 minutes presentation
OR
- I have a 5 minutes presentation?

[emsr2d2]

do we say:
- I have a 5 minutes presentation
OR
- I have a 5 minutes presentation?

When it's used as an adjective like this, we remove the "s", but we use a hyphen.

I have a five-minute presentation.
My presentation lasts five minutes.

I'm taking a four-week holiday.
I'm going on holiday for four weeks.