<h2>
8)</h2>
108° + 80° + 96° + (8x + 4)° = 360°
{in quadrilateral interior angles that add to 360°}
108° + 80° + 96° + (8x)° + 4° = 360°
288° + 8°·x = 360°
8°·x = 72°
x = 9
<h3>
A.: A) 9</h3>
<h2>
9)</h2>
(14x + 8)° = (15x + 3)°
{in parallelogram opposite angles are equal}
14°·x + 8° = 15°·x + 3°
8° - 3° = 15°·x - 14°·x
5° = (15 - 14)°·x
5° = 1°·x
x = 5
m∠K = (15x + 3)° = (75 + 3)° = 78°
<h3>
A.: D) 78°</h3>
<h2>
10)</h2>
(8x - 6)° + (19x - 3)° = 180°
{Angles laying at one side of paralleogram are supplementary angles, so they add up to 180°}
8°·x - 6° + 19°·x - 3° = 180°
(8° + 19°)·x = 180° + 6° + 3°
27°·x = 189°
x = 7
m∠R = m∠T = (19x - 6)° = (19·7 - 6)° = 130°
<h3>
A.: A) 130°</h3>
<h2>
11)</h2>
XE = EZ and XZ = XE + EZ
{The diagonals of a parallelogram bisect each other}
2x - 11 = x + 1
2x - x = 1 + 11
x = 12
XZ = 2x - 11 + x + 1 = 3x - 10 = 3·12 - 10 = 26
<h3>
A.: D) 26</h3>
<h2>
12)</h2>
DE = CF
{Opposite sides of parallelogram are equal in length}
8x - 1 = 6x + 5
8x - 6x = 5 + 1
2x = 6
x = 3
DE = 8x - 1 = 8·3 - 1 = 23
<h3>
A.: A) 23</h3>
