100
On card #7, line l and m are parallel
Prove Angle 2 + Angle 8 + Angle 9= 180
In answer = is the congruent symbol.
Angle 2 = Angle 2:Reflexive Property
Angle 1 = Angle 9:Alt.Interior Angles
Angle 3 = Angle 8:Alt. Interior Angles
Angle 1+ Angle 2+ Angle 3 =180: Forms straight Line
Angle 2+ Angle 8+ Angle 9= 180: Substitution