First off you need to know that 1 yard is equal to 3 feet.
In order to know how many feet each bow requires, you'll need to use the cross product method :
1 yard = 3 feet
0.5 yard = x feet
(3 × 0.5) ÷ 1 = x feet
1.5 ÷ 1 = x feet
1.5 = x feet
Since now you know that one bow requires 1.5 feet of fabric and you want to know how many feet of ribbon Jeanne must by to make 84 bows, you can use again the cross product method, or you can just multiply the amout of fabric required for one bow (1.5) by the number of bow you want to make (84) :
1.5 × 84 = 126
The answer is: Jeanne must buy 126 feet of fabric in order to make 84 bows.
There you go! I really hope this helped, if there's anything just let me know! :)
