Question 5384
convert the flower bed from yardage to feet by multiplying by 3 (3 feet in a yard) 
Length = 6*3 or 18 feet
Width = 1*3 or 3 feet

then use the formula:
Perimeter = 2*length + 2*width

Perimeter = 2(18)+2(3)
perimeter = 36+6
Perimeter = 42 feet

But you want a double layer of edging, so you will need:
2*42 feet of edging
84 feet of edging.

If edging costs 2.32 per foot (12"stone = 1 foot)
84 feet*$2.32=$194.88 total