ANSWER
Transitive property of equality.
EXPLANATION
According to the transitive property of equality,
if
a=b and b=c, then a=c.
Therefore,
if x=y and y=10, then x=10 is an example of transitive property of equality.
Well lets try using negatives and positives, negatives for underground positives for above. -6 + 14 = 8 then 8 - 11 = -3. When Herman finally stops climbing he is 3 feet below ground level.