The answer for finding the slope is -1/2
In a parallelogram, the opposite angles will be congruent to each other.
In this parallelogram, angles B and C are congruent, and angles A and D are congruent.
We will work on angles B and C first. Set the two angles to equal each other:
![12x + 6 = 6x + 66](https://tex.z-dn.net/?f=%2012x%20%2B%206%20%3D%206x%20%2B%2066%20)
Subtract 6 from both sides:
![12x = 6x + 60](https://tex.z-dn.net/?f=%2012x%20%3D%206x%20%2B%2060%20)
Subtract 6x from both sides:
![6x = 60](https://tex.z-dn.net/?f=%206x%20%3D%2060%20)
Divide both sides by 6 to get x by itself:
![\boxed{x = 10}](https://tex.z-dn.net/?f=%20%5Cboxed%7Bx%20%3D%2010%7D%20)
x will equal 10.
Set angles A and D to equal each other:
![54 = 3y](https://tex.z-dn.net/?f=%2054%20%3D%203y%20)
Divide both sides by 3 to get y by itself:
![\boxed{y = 18}](https://tex.z-dn.net/?f=%20%5Cboxed%7By%20%3D%2018%7D%20)
y will equal 18.
The x and y values that make this quadrilateral a parallelogram will be x = 10, and y = 18.