Answer:
8L - 2 = P
Explanation:
Please, just one question per post. I'll focus on #15
As a reminder, the formula for the perimeter of a rectangle is
P = 2L + 2W, where L is the length and W the width.
Next, we represent the width in terms of the length: W = 3L - 1.
We want the perimeter of this rectangle in terms of the length, L, with the width, W, not appearing in the final result.
Here P = 2L + 2W = 2L + 2(3L - 1), or
P as a function of L = 2L + 6L - 2 = 8L - 2 = P