Given,

In a parallelogram ABCD

∠D= 135^∘

∠C + ∠D = 180^∘.. (supplementary angles)

∠C = 180^∘ - 135^∘ = 45^∘

∠C = ∠A and ∠D = ∠B.. (Opposite angles of parallelogram)

∠A = 45^∘

∠B = 135^∘