Answer:
20 meters below sea level
Explanation:
The sea level is Reference point, any point below the sea level will be negative and any point above the sea level will be a positive
She started at 27 meters below sea level on Monday =-27 meters
Tuesday she went up 10 meters from -27=-27+10=-17, 17 meters below sea level. She also descended 3 meters below -17 m=-17-3= -20 meters
Final position on Tuesday= -20 meter or 20 meters below sea level