Answer:
∠6 = 54°
Step-by-step explanation:
Since b and c are parallel lines, then
∠8 = 13x + 9 ( alternate exterior angle ) and
∠6 = 5x + 9 ( vertical angles )
∠6 and ∠8 form a straight angle and are supplementary, thus
13x + 9 + 5x + 9 = 180, that is
18x + 18 = 180 ( subtract 18 from both sides )
18x = 162 ( divide both sides by 18 )
x = 9
Hence
∠6 = 5x + 9 = (5 × 9) + 9 = 45 + 9 = 54°
