When does deg get mutated to ddeg in numbers such as un ar ddeg?
"Ar" is one of twelve major prepositions that cause soft mutation. These are: am, ar, at, dan, dros, drwy, heb, i ,o gan, wrth, hyd. (Don't worry too much about how each is used yet).
Why is the first translation given ‘mod i’?
As a matter of fact, what the heck is up with all those different copulæ?!