Answer:
-30 is a debt of 30$
+30 is 30 meters above sea level
+6 is 6 units to the right of 0 on the number line
-15 is 15 meters below sea level
+15 is a profit of 15$
Explanation:
above sea level means positive(+)
below sea level means negative(-)
profit means you gained (+)
debt means to take(-)