To solve for $X$, we can use the inverse matrix method: $X = A^{-1}B$.
First, we need to find the inverse of matrix $A$. We can use MATLAB to do this:
```MATLAB
A = [1 1 1; 0 2 5; 2 5 -1];
A_inv = inv(A);
```
Now, we can multiply $A^{-1}$ with matrix $B$ to
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