"It costs seventeen pence."
Translation:Mae hi'n costio un deg saith ceiniog.
Why is "costio" not mutated, is it because it's a word borrowed from English?
verbs never mutate after yn. The only times yn causes mutation is nasal with place names e.g Yng Nghaernarfon, and soft with nouns and adjecitves, Yn fach/Yn gath
Thank you. In that case I think there may be a mistake in my dictionary! The Oxford Modern Welsh Dictionary gives as an example sentence "faint mae'r rhain yn gostio?" (what do these cost) Should it actually say "faint mae'r rhain yn costio?"?
I believe that the second one is definitely correct. But there may be some reason that that sentence would mutate (To the befuddlement of modern speakers and learners alike) historically e.g a possessive that has been dropped .
Why is Mae hi'n costio dwy ar bymtheg ceiniog not acceptable here? I get that Duolingo prefers decimal to vigesimal numbers and I made "it" female instead of male but both of these should be acceptable, no?
Because in the old number system the thing being counted is wedged in between when the number is made up using more than one word, (not my best explanation) i.e. "dwy geiniog ar bymtheg" Though really you should stick with decimal for anything other than dates, age and time (maybe some other stuff too but I can't remember right now).