You're starting at 400. Each time you're cutting in half.
So the common ratio is 1/2 which means the equation is

which is in the geometric sequence format. So the answer is choice D
Answer:
43
Step-by-step explanation:
18x+7
=18×2+7
=36×9
=45
8 units
Circumference = pi * 2 * radius
50.24 = 3.14 * 2 * radius
50.24 = 6.28 * radius
8 = radius
Answer:
B
Step-by-step explanation:
Hope this helps