The integer that represents Marcus location relative to the surface is -18 and Marcus has to go 18 meters to return to the surface
The depth is given as
Depth = 18 meters below sea level
Below sea level is represented as negative
So, we have
Depth = -18
Hence, the integer that represents Marcus location relative to the surface is -18
The distance to return to the surface is
Distance = |Depth|
This gives
Distance = |-18|
Evaluate
Distance = 18
Hence, Marcus has to go 18 meters to return to the surface
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