512, the formula for volume is length x width x height :)
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:
10. 7n - 1 < -8
Isolate the variable, n. Do the opposite of PEMDAS. Treat the < as equal sign, what you do to one side, you do to the other. First, add 1 to both sides:
7n - 1 (+1) < - 8 (+1)
7n < - 8 + 1
7n < - 7
Isolate the variable, n. Divide 7 from both sides:
(7n)/7 < (-7)/7
n < -7/7
n < -1
n < -1 is your answer.
11. 3 > -7v + 4v
Combine like terms, then isolate the variable, v. First, add -7v and 4v together.
3 > (-7v + 4v)
3 > (4v - 7v)
3 > (-3v)
Isolate the variable, v. Divide -3 from both sides. Note that since you are dividing a negative number, you must flip the sign:
(3)/-3 > (-3v)/-3
3/-3 > v
-1 < v
v > -1 is your answer.
~
The 6 terms of the series are
... 15, 14, 13, 12, 11, 10
The sum of them is 75.
_____
You could make use of the formula for the sum of the terms, or you could work out the sum from the given expression. It is easier just to list the terms and and them up.
Answer:
x = 4
Step-by-step explanation:
If y = 36, that means the original y = 18 was multiplied by 2. So, we have to multiply x = 2 by 2 as well.
2 * 2 = 4, so x = 4