*BRAINIEST & 20 POINTS*

x = 21

y = 114

Step-by-step explanation:

Here, we are to find the values of x and y

Mathematically;

3x - 15 + 6x + 6 = 180

reason for this is that opposite interior angles are supplementary, they add up to 180

9x-9 = 180

9x = 180 + 9

9x = 189

x = 189/9

x = 21

Also;

3x-15 + y + 18 = 180

Reason for this is that angles on a straight line are supplementary

Recall, x = 21

3(21)-15 + y + 18 = 180

63-15 + y + 18 = 180

y = 180-66

y = 114 degrees

the solution is 12x-6y