[tex]E=h\nu[/tex]
which is the energy for one photon, then can you see what the energy of many photons is??
[tex]E=nh\nu[/tex]
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
[tex]E=\frac{nhc}{\lambda}[/tex]
where lambda is
[tex]\lambda=2d\sin\theta[/tex]
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,
[tex]E=\frac{n\hbar^{2}k^{2}}{2m}[/tex]
where
[tex]k=\frac{2\pi}{\lambda}[/tex]
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
best wishes
Newo