I'm German myself but this fragment doesn't make sense (or rather, the second sentence doesn't make sense combined with the first) without any context.
Do you have the complete sentence, by any chance?
Separately, the translations would be like this:
"der wäre mitgegangen" --> "he* would have gone with us / joined us"
* Note that I translate "der" mit "he" because of lack of context; since German pronouns match grammatical gender there's a chance that whatever "der" refers to translates to "it" in English. Please also note that the use of "der" is colloquial, the "proper" way to say it would be "er" - this is NOT an article.
"dann hätte der auch raus müssen" --> "then he would have had to go out / get out"
Answers & Comments
I'm German myself but this fragment doesn't make sense (or rather, the second sentence doesn't make sense combined with the first) without any context.
Do you have the complete sentence, by any chance?
Separately, the translations would be like this:
"der wäre mitgegangen" --> "he* would have gone with us / joined us"
* Note that I translate "der" mit "he" because of lack of context; since German pronouns match grammatical gender there's a chance that whatever "der" refers to translates to "it" in English. Please also note that the use of "der" is colloquial, the "proper" way to say it would be "er" - this is NOT an article.
"dann hätte der auch raus müssen" --> "then he would have had to go out / get out"
...he would have gone with (them/him/her), then he would have had to get out, as well.
Who would have gone, then he would have had to get out