Perimeter = 406
Length = 4w - 7 (7 yds less than quadruple the width)
Width = w
P = 2(L+W)
406 = 2(4w - 7 + w)
406 = 2(5w - 7)
406 = 10w - 14
406 + 14 = 10w
420 = 10w
42 = w
now substitute 42 for w in the expression 4w-7 to find the length:
L = 4(42) - 7
L = 168 - 7
L = 161
Check to make sure dimensions add up to perimeter of 406
P = 2(161 + 42)
P = 2(203)
P - 406
Dimensions are Length = 161, Width = 42