Answer:
$21
Step-by-step explanation:
40% of 15 is 6, and 15 + 6 is 21
Octagans have 8 sides.
Perimeter is thought of as the length a piece of string would be if it was layed around the edges of the shape.
There are 8 sides, each 12units in length.
Perimeter=8*12=96units