Question

3 foot long sandwich for a party. She cuts the sandwich into pices, with each piece being 12 foot long how many pieces does she get

Answer 1

3 assuming that you meant 12 inches long instead of each piece being 12 feet long.
You would need to know that 1 foot= 12inches which means that every piece is really a foot long.
So, 3 foot long sandwich÷ 1 foot per piece= 3 pieces

Answer 2

If the answer is 12 inches long the answer would be 3. She would have 3 sandwiches.

12 inches = 1 foot