Answer:

Step-by-step explanation:
Given


Dimension of unpainted area:
--- Square
Required
Determine an expression to solve for x
First, calculate the area of the unpainted space;



The unpainted area, added to the painted area, equals the total area.
So, we have:


Hence, the expression is: 
Answer:
f1: 0.440, f2: 0.931, f3: 1.519
Step-by-step explanation:
To solve the system of equations we need to use the inverse of matrix A, as follows:
A x F = C
A^-1 x A x F = A^-1 x C
I x F = A^-1 x C
where I is the identity matrix.
The inverse of A is:
1.450 -0.392 -0.090
A^-1 = -0.074 -0.022 0.1536
-0.406 0.7122 -0.060
(computed with Excel)
The multiplication between the inverse of A and C gives:
0.440
A^-1 x C = 0.931
1.519
(computed with Excel)