I would assume you would do base*width*weight to get your area.
m₁ = mass hanged initially = 0.2 kg
x₁ = initial stretch in the spring = 8 cm = 0.08 m
k = spring constant of the spring
the weight of the mass hanged is balanced by the spring force by the spring hence
Spring force = weight of mass hanged
k x₁ = m₁ g
k (0.08) = (0.2) (9.8)
k = 24.5 N/m
m₂ = mass hanged later = 0.5 kg
x₂ = final stretch in the spring = ?
k = spring constant of the spring = 24.5 N/m
the weight of the mass hanged is balanced by the spring force by the spring hence
Spring force = weight of mass hanged
k x₂ = m₂ g
(24.5) x₂ = (0.5) (9.8)
x₂ = 0.2 m = 20 cm
Write the system in augmented-matrix form:
![\left[\begin{array}{ccc|c}2&2&4&16\\5&-2&3&-1\\1&2&-3&-9\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D2%262%264%2616%5C%5C5%26-2%263%26-1%5C%5C1%262%26-3%26-9%5Cend%7Barray%7D%5Cright%5D)
Multiply through row 1 by 1/2:
![\left[\begin{array}{ccc|c}1&1&2&8\\5&-2&3&-1\\1&2&-3&-9\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C5%26-2%263%26-1%5C%5C1%262%26-3%26-9%5Cend%7Barray%7D%5Cright%5D)
Add -1(row 1) to row 3, and add -5(row 1) to row 2:
![\left[\begin{array}{ccc|c}1&1&2&8\\0&-7&-7&-41\\0&1&-5&-17\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C0%26-7%26-7%26-41%5C%5C0%261%26-5%26-17%5Cend%7Barray%7D%5Cright%5D)
Swap rows 2 and 3:
![\left[\begin{array}{ccc|c}1&1&2&8\\0&1&-5&-17\\0&-7&-7&-41\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C0%261%26-5%26-17%5C%5C0%26-7%26-7%26-41%5Cend%7Barray%7D%5Cright%5D)
Add -7(row 2) to row 3:
![\left[\begin{array}{ccc|c}1&1&2&8\\0&1&-5&-17\\0&0&-42&-160\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C0%261%26-5%26-17%5C%5C0%260%26-42%26-160%5Cend%7Barray%7D%5Cright%5D)
Multiply through row 3 by -1/42:
![\left[\begin{array}{ccc|c}1&1&2&8\\0&1&-5&-17\\0&0&1&\frac{80}{21}\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C0%261%26-5%26-17%5C%5C0%260%261%26%5Cfrac%7B80%7D%7B21%7D%5Cend%7Barray%7D%5Cright%5D)
Add 5(row 3) to row 2:
![\left[\begin{array}{ccc|c}1&1&2&8\\0&1&0&\frac{43}{21}\\0&0&1&\frac{80}{21}\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%261%262%268%5C%5C0%261%260%26%5Cfrac%7B43%7D%7B21%7D%5C%5C0%260%261%26%5Cfrac%7B80%7D%7B21%7D%5Cend%7Barray%7D%5Cright%5D)
Add -1(row 2) and -2(row3) to row 1:
![\left[\begin{array}{ccc|c}1&0&0&-\frac53\\0&1&0&\frac{43}{21}\\0&0&1&\frac{80}{21}\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D1%260%260%26-%5Cfrac53%5C%5C0%261%260%26%5Cfrac%7B43%7D%7B21%7D%5C%5C0%260%261%26%5Cfrac%7B80%7D%7B21%7D%5Cend%7Barray%7D%5Cright%5D)
So the solution to the system is

The volume for a cube is the cube of any side. side^3
If each sides measures 1 foot, the volume would be 1 ft^3.