Which lines are parallel? Justify your answer.
Lines a and b are parallel because their alternate exterior
angles are congruent.
Lines a and b are parallel because their same side
exterior angles are supplementary.
Lines e and fare parallel because their alternate exterior
angles are congruent.
Lines e and fare parallel because their same side exterior
angles are congruent
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check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

i got 142 as my answer

step-by-step explanation:

$12. that is my answer.