Consider the following sentence:
Seit zwei Jahren tausche ich meine alten aber noch guten Sachen hier und bin begeistert.
In this sentence, as per my understanding, we have a Akkusative Feminine object "Sachen". (https://www.duden.de/rechtschreibung/Sache) If this is true, then shouldn't the endings of adjectives be "-e" as in "alte" and "gute" as compared to "alten" and "guten".
What am I missing? Can any one please explain why my A2 book has placed "alten" and "guten" in this sentence?
Thanks in advance