Answer:
D. 2
Step-by-step explanation:
DEFG is a trapezoid and AB is its Midsegment.
Therefore,

Answer: x=1 or x=-3
Step-by-step explanation:
Quadratic formula is 
a=1 b=2 c=-3
Substitute

Answer:
x = 7
Step-by-step explanation:
QY = 5x
YZ = 18
QZ = 53
Thus:
QY + YZ = QZ (segment addition postulate)
5x + 18 = 53
5x = 53 - 18 (subtraction property of equality)
5x = 35
Divide both sides by 5
x = 7