Point A is 4.2-(-15.6) =19.8 (m) higher than point B;
Point A is 4.2-(-30.5) = 34.7 meters higher than point C. 。
A: Point A is 19 meters higher than Point B and 34 meters higher than Point C. 。
So the answer is:
19.8 (m); 34.7 (meters)