‘n’ is a straight line which intersects l and m straight lines. ∠1 + ∠4 < 180° and ∠2 + ∠3 > 180°.
If l and m, produced by the side of ∠1 and ∠4 they meet at p.
If ∠1 + ∠4 < 180° and ∠2 + ∠3 > 180°, then l and m straight lines do not meet even produced, means they are parallel lines.
