Answer:
B. 10 1/2 feet
Explanation:
We are told that she taped 7 boxes.
We are also told that she uses 1 1/2 feet of tape to close each box.
Therefore, the length of tape she will need to use for the 7 boxes will be the product of 7 boxes and 1 1/2 feet of tape per box:
L = 1 1/2 * 7 = 3/2 * 7 = 21/2 = 10 1/2 feet.
She will need to use 10 1/2 feet of tape.