Question 1179537
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<pre>
The same side interior angles, formed by two parallel line and a transversal line,
always sum up to 180 degrees.


So we write

    A + B = 180,

    30 + B = 180,

    B = 180 - 30 = 150 degrees.


<U>ANSWER</U>.  B = 30 degrees.
</pre>

Solved and explained.


The plot in the post by @mananth is irrelevant to this problem,
so you better ignore it for the safety of your mind.