Yes, math is called maths in Welsh.
Mathemateg
You can say "I am Welsh" by simply stating "I am Welsh" in English. In Welsh, you would say "Cymraeg ydw i" (I am Welsh).
'Our Friends' in Welsh is 'Ffrindiau Ni' :)
To say "your house" in Welsh, you would say "eich tลท".
Cymraeg
"Na" is the word for "no" in Welsh.
"y diwedd" is how you say it in Welsh language.
In America it is math, in most European countries it is maths
In Welsh, you would say "Rwy'n cytuno" to say "I agree."
Welsh dragon in Welsh is "draig Goch".
You can say "it's nice" in Welsh as "mae'n braf."