No way is this correct!
5-3/2-9/4=1 1/4
The answer is C.
Sample space = {HH, HT, TH, TT}
The answer to your question is Scientific Notation
Answer: 
Reason: The graph shows all values that are z = -10 or larger.
The closed endpoint at -10 indicates we include it with an "or equal to".
If it was an open hole endpoint, then we'd say z > -10 instead.