Answer:
∠1 = 120°
Step-by-step explanation:
Since the 2 lines are parallel
Angles 5x + 15 and 3x - 3 are same- side interior angles and are supplementary, thus
5x + 15 + 3x - 3 = 180, that is
8x + 12 = 180 ( subtract 12 from both sides )
8x = 168 ( divide both sides by 8 )
x = 21
Hence
∠1 = 5x + 15 ( corresponding angles )
= (5 × 21) + 15 = 105 + 15 = 120°
