Should be جَدَّتُكَ
But the grammar taught in the this course shows differently. like this one
Hovering over خلفك doesn't show the meaning...
(ghalfaka) meaning is missing. please fix it. thanks
It's khalfaka though. And for what it's worth, it means "behind you (male, singular)."
Should accept Granny and Grandma as synonyms to Grandmother!!
Behind you is خلفك
خلف is back or behind
And the ك is referring to you like possession or prepositioning like "your" behind or behind "you"