which is the energy for one photon, then can you see what the energy of many photons is??
where n is the number of photons, hence rearrage to get n,
i presume the photons get diffracted as they go through the hole in which case
where lambda is
because you haven't given information on what you are given ie what values you have, I will also give you this for a particle,
and as before [tex]\lambda=2d\sin\theta[/tex]
also when asking questions, it is best to put more into them, your own workings and understanding and also a bit more in about the question, it is not easy to understand what you are asking with only 2 lines of writing