Question

My question is #6 but I am confused on it

Answer 1

`\begin{gathered} a\parallel b,b\parallel c,\Rightarrow a\parallel c \\ \text{ Assume:} \\ a\\parallel c \\ If_{\text{ }}a\\parallel c \\ Then_{\text{ }}a\\parallel b_{\text{ }}or_{\text{ }}b\\parallel c \\ \end{gathered}`

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