Answer:
A. 57m B. 130m
Step-by-step explanation:
For problem A:
87m up a cliff - 30m up a cliff = 57m up a cliff
These are all positive values
For problem B:
100m above is talking about a positive value, making this a positive number
30m below is talking about a negative value, making this number -30
0 meters represents the surface
As you can see, this is forming a number line as of which
below the surface------------------------0m-------------------------above the surface
by substitution,
-30-----------------------------------------------0-------------------------------100
therefore, 100 - -30 = 130 meters
