Answer:
C
Step-by-step explanation:
They are essentially asking us to solve:

Solving this equation for x tells us that it will take around 80.1 years for the materials in the vault to reduce to 357 pounds.
O is the midpoint of Reason: Defintiin of a midpoint
Area of Base x Height
Area of a circle is PI x R squared
Radius is 3
Area of Base is 9Pi
9Pi x Height
Height is 6
9pi x 6 =
54 pi.
Answer:
Fraction: x = 247/21
Decimal: 11.76
Mixed Number: 11 16/21
Step-by-step explanation:
Brainliest Please!!