The subject (N1) of the clause in which a noun (N2) is modified by the preceding verb can be marked by either が or の.
テレビが ある へやは どこですか。
Where is the room which has a TV?
テレビの ある へやは どこですか。
Where is the room which has a TV?
わたしが かいた えを あげます。
I'll give you the picture/drawing that I painted/drew.
わたしの かいた えを あげます。
I'll give you the picture/drawing that I painted/drew.
