"All of them are red."
Translation:Elles sont toutes rouges.
Even though I agree that the translation is quite far from the original, the word order has to be changed anyway. The expression Tous d'eux/Toutes d'elles doesn't exist in French. However, what could be possible is something like "Elles toutes sont rouges" or "Toutes sont rouges"
You have mixed genders - toutes is feminine but eux is masculine. But would this sentence use the disjunctive pronoun? I very much doubt it. Anyway "them" is the direct object. Even "Toutes de les sont rouges'' sounds weird, hence the change of word order:
"Elles sont toutes rouges / Ils sont tous rouges "
As we don't know what they/them are, the sentence can be written in the masculine as well.
Someone asked a very similar question on this WordRef forum thread:
Also, as "All of them are red", it would be interesting to know if :
"Tous (toutes) sont rouges" would be accepted.
Did this sentence come up in review or a specific lesson?
Duolingo keeps stating that the correct translation starts with "Elles"; however, it does not give it as an option. It only give "Ils" as the choice. I have reported it and hope it will be corrected. However, since it won't accept the only possible answer, it will not let me finish the lesson.
Is "tous" available?
No one reporting the lack of "elles" has stated whether or not it is. If it is, it goes with "ils", and that's what you should choose, not "toutes".
Your other option, at least on the web browser version, is to choose not to use the word bank. Just select "use keyboard" and type a correct translation instead.
"Ce sont" is used when the complement is a noun: "ces sont des robes".
"Ils/Elles sont" is used when the complement is an adjective: "elles sont tou(te)s rouges".
In English, 'they are all red' is not the same as 'all of them are red.' This is a rephrasal of the underlying meaning - which I agree is the same - and a different construction. I do feel a bit cheated though. If you want me to translate 'they are all red' i can do that with no trouble at all. I was trying to find a way of using 'eux', so would 'tous d'entre eux sont rouges' work?