The answer would be the <u><em>ASA Postulate</em></u> because of the fact that the two opposite angles are congruent and the line crossing the rectangle is congruent to itself (reflexive Property)
The ASA (Angle-Side-Angle) congruence postulate states that if two triangles have two angles and the included side (the side between the vertices of the two angles) congruent, then the triangles are congruent.
The two congruent angles are ∠ACB ≅ ∠CAD and ∠CAB ≅ ∠DCA. The included side is segment AC
All you have to do is divide 72 by 90n and it will give you .8, move the decimal two places to the right to give you 80 and subtract 80 from 100 to get 20
