Sketch the rectangle very quickly,
2W + 8 (length)

 W (width)

Length (L) = 2 times the width + 8 more = 2(W)+8
Width = W
Perimeter = 2(W) + 2(L) now substitute in the Length in terms of Width above
166 = 2(W) + 2(2W+8) use distributive property
166 = 2W + 4W +16
150 = 6W
25 = W The width of the field is 25 yards
2(25) + 8 = Length The length of the field is 58 yards