Answer:
bro just search it on mathaway or calculator soup
Step-by-step explanation:
If you would like to calculate the arithmetic mean, geometric mean, and harmonic mean from the following averages, you can calculate this using the following steps:
averages: 56.4, 59.8, 55.8
the number of values: 3
arithmetic mean:
(56.4 + 59.8 + 55.8) / 3 = 57.33
geometric mean:
(56.4 * 59.8 * 55.8)^(1/3) = 57.31
harmonic mean:
3 / (1/56.4 + 1/59.8 + 1/55.8) = 57.28
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.
Answer:
The answer is d. Hope this helps :D
Please mark brainliest!