Hello, Zoe,
I know it is easy to get lost on Stoichiometry. Unfortunately, my step-by-step simplification is too long for this reply box. I've uploaded it to Google Docs and you can get it here: https://docs.google.com/document/d/1RQt9Oop1G2xAFOy9zFIZC6XDryt_Nd8R2kFuhPTJIWA/edit?usp=sharing
I think you'll find the approach I take helps simplify the process and makes it easier to avoid mistakes. Try it, and let me know if you'd like more help.
Bob