Step-by-step explanation A closed interval is one that includes its endpoints,. An open interval is one that does not include its endpoints
![\begin{gathered} (a,b)\rightarrow open \\ \lbrack a,b\rbrack\Rightarrow closed \end{gathered}]()
Step 1
a)

this inequlity represent all the values greater or equal than zero , so from zero to positive infinite

Step 2
b)

all the values smaller or equal than 8, so from negative infinite to eighth

c)
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d)

all the values greater or equalto 12

e)

all the values greater or equal to -8, hence

I hope this helps you