Can someone help me with this one question? (Number 10.)

All you have to do is 8 * 2, because an octagon has 8 sides.
8 * 2 = 16
Hope this helps!
Since its an octagon, there's 8 sides. Each side is 2 feet long. Since you are trying to find the perimeter of the sign, you would multiply 8x2. So Mandy will use 16 feet of tape on each stop sign.