Same side interior angles CONVERSE also called consecutive interior angle CONVERSE.
IF (x - 30) + (x + 50) = 180 then, line line n || m.
x - 30 + x + 50 = 180
2x + 20 = 180
subtract 20 from both sides
2x = 160
divide both sides by 2
x = 80
IF (x - 30) + y = 180, then k || j.
(80 - 30) + y = 180
50 + y = 180
subtract 50 from both sides
y = 130
