1: If line AD = 8 cm, and line BC = .5x + 14, what is the value of x?

2: Line AD = 8cm, Line DC = 6cm, the height of the parallelogram is 5 cm. What is the area and perimeter of the parallelogram?

Question 1:
In a parallelogram, each two opposite sides are equal.
This means that:
AD = BC
8 = 0.5x + 14
8 - 14 = 0.5x
-6 = 0.5x
x = -12

Question 2:
Part 1: getting the perimeter:
In a parallelogram, each two opposite sides are equal, this means that:
AB = CD = 6 cm
AD = BC = 8 cm 
Perimeter of a parallelogram is the summation of its four sides, therefore:
perimeter = 6 + 6 + 8 + 8 = 28 cm

Part 2: getting the area:
area of the parallelogram = base * height
In the given, we have:
base = CD = 6 cm
height = 5 cm
Therefore:
area = 5 * 6 = 30 cm²
Note:
If you have a drawing where the base is AD, then you would substitute with base = 8 cm in the equation

Hope this helps :)