supplement angles are angles whose sum equal to 180°.
m∠T = (3y-36)° = 180° - 36° = 144°
since m∠T is equal to 144°, then its supplement must equal to 36°.
among the choices, the correct answer is:
(216 - 3y)°
3y is equal to 180°. so, 216 - 180 = 36°