Answer:
13.34
Step-by-step explanation:
5.15+5.15=10.30
+3.04=13.34
Check the picture below, let's use those two points on the line to get its slope.

I believe the ansr would be (-6,-4) I say this becuase if it's positive on the y axis the X axis will be negative and if it's being reflected the coordinates will be backwards. If this answer is wrong I'm truly sorry, but I hope this helps!