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://img.qammunity.org/2019/formulas/mathematics/middle-school/tq22j9gihjeoagvgjjwbpa9r2k66hkticr.png)
Subtract 6 from both sides:
![12x = 6x + 60](https://img.qammunity.org/2019/formulas/mathematics/middle-school/ke7dgyexxxi578s2rw49mlojdqneiah52v.png)
Subtract 6x from both sides:
![6x = 60](https://img.qammunity.org/2019/formulas/mathematics/middle-school/5gp3c7lsor4uoh6va3hlyzfof6264k3vft.png)
Divide both sides by 6 to get x by itself:
![\boxed{x = 10}](https://img.qammunity.org/2019/formulas/mathematics/middle-school/q6twkfkkiujd837qadm1qb0dvmnqp3dgdj.png)
x will equal 10.
Set angles A and D to equal each other:
![54 = 3y](https://img.qammunity.org/2019/formulas/mathematics/middle-school/a6xusvxagzhjzsoii5lpdo4p76hel1mlgd.png)
Divide both sides by 3 to get y by itself:
![\boxed{y = 18}](https://img.qammunity.org/2019/formulas/mathematics/middle-school/rqr7koxkwm0ehlh8bpwwkxa8c64onoxe4i.png)
y will equal 18.
The x and y values that make this quadrilateral a parallelogram will be x = 10, and y = 18.