"They take off their coats."
Translation:Ils enlèvent leur manteau.
Hi Kim! Thanks for directing me here. :) First a small correction: I'm a contributor, but not a moderator (for this course). Contributors are responsible for the content of the course; they add/remove/edit sentences, clear reports, and so on. Moderators are responsible for keeping the forums clean. There are, of course, lots of people who have both roles (I do for PL<-EN), but not everyone does.
Now that I've been picky about your terminology ;) "leurs manteaux" is accepted, and has been. But there are reports for "leur manteaux" with "leur" in singular, which is, of course, wrong. It's probable that those having their answer with "manteaux" rejected have done the same thing and used "leur".
How would they say, "They take off their coat." Even in English you'll have to clarify that they have only one coat between them. I guess it's "Ils enlèvent (même?) leur seul manteau." This is after the pattern of, "Les Gorgones voient même partageant un seul œil et ont une seule dent pour trois."
Maybe "deux chevaliers partager le même cheval." -- https://fr.wikipedia.org/wiki/Sceaux_des_Chevaliers_du_Temple#Les_deux_chevaliers
As for coats a lot comes up in the negative, but only regarding possession: "être sort embarrassés de n'avoir à eux deux qu'un seul manteau" "ils n'a voient à eux trois qu'un seul manteau" "n'ayant entre eux qu'un seul manteau"
If they're all wearing the same coat on a show, this is likely the "totem pole trench" or "two men one dress" trope. You have to admit only one head sticks out though, so "avec" or to form a duo seems to suffice: "avec Simplet [Dopey] sur ses épaules, un cavalier de taille normale pour danser de façon endiablée avec Blanche-Neige [Snow White]." No mention I can find of them putting on whatever it was they were wearing, nor in Sleeping Beauty, the old Disney versions that is . . .
Japanese used to ride on wooden saddles for up to three riders called sambo kojin like the god. No translation into French, no mention in French, that I can find . . .
Most French nouns and adjectives can be pluralised by adding an ending -s, like in English. Those that can't be pluralised like this normally will have plural forms that end in -x. For instance, most nouns ending in -al or -ail change to -aux.
un animal ⇒ des animaux ("animals")
le travail ⇒ les travaux ("work")
Similarly, masculine singular adjectives ending in -al take on -aux endings in the plural. However, feminine singular adjectives ending in -ale simply add an ending -s.
général -> généraux ("general")
générale -> générales ("general")
idéal -> idéaux ("ideal")
idéale -> idéales ("ideal")
Add -x to the end of most nouns that end in -au, -eau, and -eu to pluralise them.
un tuyau ⇒ des tuyaux ("pipes")
mon chapeau ⇒ mes chapeaux ("my hats")
le feu ⇒ les feux ("fires")
The plural forms of -au, -eau, and -eu words are homophones of their singular forms. In general, the best way to tell if a noun is plural is to listen carefully to its article or determiner. If you hear les or des, or the possessives mes, tes, ses, nos, vos, leurs, or the demonstrative ces, it's plural. Otherwise, it's probably singular.
From Tips & Notes : Unit: Irregular Plurals