If I have 2 pens and I want to say all of them are green, I can say "Both of them are green" but if I have 3 pens should I use "Triple of them are green" or "All of them are green"?
You could go with any of the following:
All 3 of my pens are green,
All (of) my 3 pens are green,
My 3 pens are all green,
The word triple as an adjective means:
When used as a verb, it means:
to triple the number 4 is equivalent to multiplying 4 by 3,
written numerically as: (4 + 4 + 4) or (4 x 3) = 12
Hope that helps.
You can say "all my 3 pens are green" to mention the number of your pens and their color, simultaneously.