One way a parallelograhm and a rhombos are diffrent

A parallelogram does not need to have all its sides equal. It just needs two pairs of equal opposite sides. A rhombus on the other hand, has to have all its four sides equal. A rhombus is actually a special form a parallelogram. So, a rhombus is always a parallelogram but a parallelogram is not always a rhombus.

Proportionally?  Not sure.  But here is a way to find out the value of x

50° + 2x+40 +4x+8 = 180°
Combine like terms
50°+ 6x + 48=180
  (now subtract 50° from both sides)
6x + 48 = 130°
(now subtract 48 from both sides
6x=82°  
x= 13.6666667° (repeating decimal)