Since ZA and YB are equal in length and the two lines are parallel to each other.
Also, we can see that YZ and AB are perpendicular to both ZA and YB, thus
YZ = AB
16x - 4 = 4 - 4x
16x + 4x = 4 + 4
20x = 8
x= 8/20 = 2/5
YB = ZA = 20x - 5 = 20(2/5) - 5 = 3
Thus, the value of x is 2/5 and length of YB is 3 units.
So, the correct answer is option A
