The fertilizer ammonium sulfate (VI) is produced by the following equation:
2NH₃ + H₂SO₄ -->(NH₄)₂SO₄
If 15kg of ammonia was used and the efficiency of the process is 85%, what is the mass of fertilizer produced?

No homework answers he here, show some work, or walk us through what you know, someone here can surely help.

Hint:

Use your moles. Some ratios, and you'll be mostly there.
Good Luck!