When two straight lines intersect, the vertical opposite angles
intersect. the other two angles are also equal. Let the known angle be
x, then the other two adjacent angles are obtained subtracting twice of x
from 360 and dividing the result by 2.
Therefore, the table can by filled as follows:
Row 1:
Given <GEF = 120°
<FEM is adjacent to <GEF, thus
<MEH is vertically opposite to <GEF and thus is equal to <GEF. Thus <MEH = 120°
<HEG is vertically opposite to <FEM and thus is equal to <FEM. Thus <HEG = 60°.
Row 2:
Given <MEH = 150°
<MEH is vertically opposite to <GEF and thus is equal to <GEF. Thus <GEF = 150°
<FEM is adjacent to <GEF, thus
<HEG is vertically opposite to <FEM and thus is equal to <FEM. Thus <HEG = 30°.
Row 3:
Given that <FEM = 25°
<FEM is adjacent to <GEF, thus
<MEH is vertically opposite to <GEF and thus is equal to <GEF. Thus <GEF = 155°
<HEG is vertically opposite to <FEM and thus is equal to <FEM. Thus <HEG = 25°.
Row 4:
Given that <HEG = 45°
<HEG is adjacent to <GEF, thus
<HEG is vertically opposite to <FEM and thus is equal to <FEM. Thus <FEM = 45°
<MEH is vertically opposite to <GEF and thus is equal to <GEF. Thus <GEF = 135°.
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