Answer:
see below
Explanation:
1. when we talk about debts
why?
because a debate is some amount of money that you don't have, it's like earn something negative
2. when we measure distance below sea level
why?
because the distance above the sea level it's like 300 meters so the opposite is -300 meters and it's understood that we talk about sea level
3. when we measure the temperature
why?
because a thermometer can go in both directions, for example in Celsius
0° it's when the water becomes ice and below that is colder than that.
I hope that i explained well enough