Rectangular swimming pool has a perimeter of (6x-6) feet and a width of x. find the length 5x-6 4x-6 2x-6 2x-3

The first thing you should know for this case is that the perimeter of a rectangle is defined as:
 P = 2L + 2W
 Where
 L = length
 W = Wide
 We then have to clear the length:
 L = (P-2W) / 2
 Substituting the values
 L = ((6x-6) -2x) / 2
 Rewriting:
 L = ((3x-3) -x)
 L = 2x-3
 
 the length is
 2x-3

(x) - (y) = (1 + 4i)

(3 + 6i) - (2 + 2i) = (1 + 4i)