Using a mixture of co2 n2 and sometimes he co2 lasers emit

Question

Here is the problem which I am struggling on, please help me!

Problem: Using a mixture of CO₂, N₂, and sometimes He, CO₂ lasers emit a wavelength of 10.8μm. At power outputs of 0.125kW, such lasers are used for surgery.

Part A: How many photons per second does a CO₂ laser deliver to the tissue during its use in an operation?

Please use as much detail as possible in your solution. Thank you.