Answer: B: 15
Step-by-step explanation:
You can get this answer using the pythagorean theorem. a^2 + b^2 = c^2
In this case, you can assume a = 9 and b = 12 (though either or would still equal 15)
√9^2+12^2 = 15
The base of the box's length would be 15 feet long.
