Given that AB || CD, intersected by a transversal, if the complement of ∠5 equals the supplement of ∠4, then the measures of ∠4 and ∠5 are
∠4 = 135o, ∠5 = 45o
90o - ∠5 = 180o - ∠4,
And ∠4 + ∠5 = 180o (Consecutive angles on same side of transversal)
Substituting the value of ∠4 in the first equation we get
∠5 = 45o
Then �∠|4 = 135o