618. Which angles are supplementary to 21? Whichare congruent to _1? SEE EXAMPLE 2zalona, 61/23/45/67/8

SOLUTION
Consider the image below
Supplementary angles are angles that sum up to 180 degree
[tex]\begin{gathered} \text{Sumplementary angles to }\angle1\text{ are } \\ \angle2\text{ and }\angle3 \\ \angle1+\angle2=180^0(sum\text{ of angle on a straight line )} \\ \angle1+\angle3=180^0(sum\text{ of angle on a straight line )} \end{gathered}[/tex]
Similarly,
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