You can plug in the numbers like 2=3(6) + b then rearrange for b so 2-18=b so the answer to your question is y=3x-16

Actually Welcome to the Concept of the plots and graphs.
Since, the x axis varies from -infinite to +infinite,
here, the y totally varies from -5 to +5,
hence, the option B.) is correct.
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The composition of a function and its inverse is always <u>x</u>.
I hope this helps! :D