"They arrived at a solution."

Umm, shouldn't "Ellos" be accepted as well as "Ellas"? Especially since there is no clue first that all of "They" are not necessarily female.

Yes, bit unfair to rule 'ellos' as wrong

Also, it should accept just llegaron, without ellos OR ellas. I just reported that.

FFS Duolingo, "they" does not specify male or female!

I agree and have reported it

Well, as of today, they still haven't fixed it. I had the same 'ellos' vs. 'ellas' problem. Hope it gets fixed soon. So frustrating!

I agree...it could have been a mixed group. I think duolingo is wrong on this..either should have been accepted.