Believe it or not, :), the width of the ribbon needs to be known to get the right answer. If the ribbon had an infinitely small width the ribbon needed would just be the perimeter.
P=2(L+W)
P=2(12+15)
P=54 in
However an infinitely small width is not something that has any practical application. For example, if the width of the ribbon were 1/2 in.
P=2((L+1)+W)
P=2(16+12)
P=56 in So the perimeter increased by 2 in when the ribbon was only 1/2 in wide.
The "infinitely small" width and the perimeter of 54 in is only a decent approximation if the ribbon were a very thin string.
Try VTR, My explanation for this answer is the question is asking to name three points on plane B and the first three options go off the B plane and if you look the last option is the only one that stays in the B plane
<span>4x +5=9x-2
9x - 4x = 5 + 2
5x = 7
x = 7/5
x = 1.4</span>
Sqrt((0-9)^2+(-12-0)^2)+sqrt((0-9)^2+(12-0)^2) using the distance formula equals sqrt(81+144)+sqrt(225)=15+15=30