"No, I do not have to go."
Translation:Nac oes, does dim rhaid i fi fynd.
"G" and "c" are what is called "Suspect Pairs" - that is they are made very closely in the mouth, so are often interchangeable in spoken speech but not so always in written. (Gosh takes me back to my linguistics course many moons ago!!!)
I know here is Cardiff my friends usually say "nag" but I get told off if I write it as "nag." It is accepted when I say it, though. Often spoken languages are like that - English is no exception.
In my uni. Welsh course notes it is written as "nac oes" and that is what we are expected to write.
"i fi" is used here in the south, in Cardiff. But a lady I go to practice speaking Welsh with, is from the north, and says "i mi" So swamae is right. Difference between N & S and we are taught both in DuoLingo.
Hope that is helpful.