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:

Subtract 6 from both sides:

Subtract 6x from both sides:

Divide both sides by 6 to get x by itself:

x will equal 10.
Set angles A and D to equal each other:

Divide both sides by 3 to get y by itself:

y will equal 18.
The x and y values that make this quadrilateral a parallelogram will be x = 10, and y = 18.
Answer:
The answer is -19
Step-by-step explanation:
Given information -19y^2 , y=-1
-19 * y^2
-19 * (-1)^2
-19 * 1 = -19
Subtract the like terms to get your answer of y^2 - 4y - 6
83.................................