A solution that is 0.45 M in NH 3 is also 0.45 M in NH 4 NO 3 . What is the pH of the solution?

A solution that is 0.45 M in NH3 is also 0.45 M in  NH4NO3. What is the pH of the solution?

I know the answer is 9.26, but I do not know how to solve. Thank you!