Part a.
The perimeter formula is: P = 2w + 2L
Your answer for part A is P = 2w + 2L
Part b.
They tell us in part b, that:
w = 6L + 20
Substitute that into what we got for part a.
P = 2(6L + 20) + 2L
P = 12L + 40 + 2L
P = 14L + 40
Your answer for partb is P = 14L + 40
Part c.
So we take what we got from part b, and solve for L.
P = 14L + 40
14L = P - 40
[tex]L = \boxed{\frac{P-40}{14}}[/tex]
That is your answer for part 3 ^
part d.
Plug in w = 32 into what we first got in part b.
w = 6L + 20
32 = 6L + 20
6L = 12
L = 2
Your answer for part d is L = 2
:D