First, let's clarify a few things. A parallelogram does not have length & width in the classic sense (i.e. like a rectangle), as those terms indicate overall dimensions.
So, for this answer I will assume that we are talking about the lengths of the two pairs of equal and parallel sides of the parallelogram.
In that case the perimeter of the parallelogram is the same as a rectangle of the same side lengths:
2a + 2b
Using the given 44 meters as the perimeter we get:
44 = 2a + 2b
Using "a" for the width, "b" for the length, and the description of the relationship between the two we get:
a = b - 6
Now we substitute b - 6 for a in the first equation and solve:
44 = 2(b - 6) + 2b | distribute the parenthesis
44 = 2b - 12 + 2b | combine like terms
44 = 4b - 12 | +12
56 = 4b | /4
14 = b
Using a = b -6 we get a:
a = 14 - 6
a = 8
Verify:
44 = 2*8 + 2*14
44 = 16 + 28
44 = 44
Checks out!