Hi, I can do it! I can show you some of my ror projects.
I am a senior web developer with 5-year exp and RoR development is my major skill as well as my favorite part.
Being a fast developer, I am sure I can finish this project within your satisfaction and I can take responsibility of maintenance of the project too.
I have read your requirements very carefully and I am very confident right now.
Just do believe me!
I will show you my ability and will satisfy you for sure.
Thank you.