For example, ∠ 1 = 45, ∠ 2 = 135, ∠ D = 45, is AB parallel to CD? Why? What about BC and DE?
AB is parallel to CD because ∠2= 135, so ∠BCD is 45 degrees, so ∠ 1=∠BCD=45, so AB//CD.
BC//DE because BCD = 45 D = 45.
So ∠BCD=∠D so BC//DE
Sorry, I can't type mathematical symbols. Let's make do with it.