Here is the sentence from the course that I am a bit confused about:
__*ek kamare kaa ek raath kaa kiraayaa kithanaa hai?*__
Why does "kamare" end in an "e" instead of an "aa". Why is it not "ek kamaraa kaa....." It seems that "kaa" changes the ending of the word "kamaraa". Is this correct and why is this so?