Answer :
1) Since Mia's place is at (5,3) therefore in the I quadrant, and a reflection across the x-axis follows this rule:
Pre-image Image
(x, y) -------------->(x,-y)
(5,3) --------------> (5,-3)
2) So, we can state that Mia is going to have his house in Quadrant II
Hence, the answer is II quadrant