Plz. Can anyone explain and tell the answer of this question.I promise I will mark it as brainliest Question.

Answer:
x = 15
y = 90
Step-by-step explanation:
Step 1: Find x
We use Definition of Supplementary Angles
9x + 3x = 180
12x = 180
x = 15
Step 2: Find y
All angles in a triangle add up to 180°
3(15) + 3(15) + y = 180
45 + 45 + y = 180
90 + y = 180
y = 90°