Answer:
I believe the answer is -28
Explanation
I gotchu bro
The answer is -28 because Liana starts at 25 below sea level (which is the same thing as -25) If she rises 9 feet, then you know to add because she is going up so your just gonna add. Next she descends 12 feet, so she went down, so subtract. So i know the answer is going to be -28 because -25+9 is -16, then imma subtract -16 and 12 so, -16 - 12= -28. There ye go