Noswaith dda, faiz! Beth ydy fy ngwaith? Athro mathemateg dw i.
(As far as verbs go, my knowledge such as it is, is mostly via Duolingo... the good thing is most.verbs don't *have* to be conjugated, just use them as is with a conjugated form of *bod* = to be, as a helper verb...)
Noswaith dda, Johano. Rhaglennwr dw i. Rydw i'n defnyddio mathemateg aml.