Answer
Option C is correct.
Length of the rectangle = 140x - 82.5
Explanation
The perimeter of a rectangle is given as
P = 2 (L + W)
where
P = Perimeter of the rectangle = 340x - 255
L = Length of the rectangle = ?
W = Width of the rectangle = 30x - 45
P = 2 (L + W)
340x - 255 = 2 (L + 30x - 45)
340x - 255 = 2L + 60x - 90
We can rewrite this as
2L + 60x - 90 = 340x - 255
2L = 340x - 60x - 255 + 90
2L = 280x - 165
Divide both sides by 2
(2L/2) = (280x - 165)/2
L = 140x - 82.5
Hope this Helps!!!