Operations with matrices

An identity matrix of size $n$ is the $n\times n$ square matrix with elements equal to $1$ on the main, or leading diagonal (the diagonal of elements $a_{i,j}$ where $i = j$, so $a_{1,1},a_{2,2},\dots a_{n,n}$) and $0$ elsewhere. For example, $X$ is a $4\times4$ identity matrix:

$X = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix}$

Look at the following matrix $A$:

$$A = \begin{pmatrix} -5 & 10 & 20 \\ 3 & 4 & -7 \\ 10 & -8 & 7 \end{pmatrix}$$Find the matrix $B$ such that $A + B$ is an identity matrix of size $3\times3$. Write the matrix $B$ to the answer field.

For example, your output may look like this

-2 3 1
1 -1 -1
3 -3 1