1. ## Find a matrix

Find a matrix A such that

[1 3 2] [ 7 1 3]
[2 1 1]A=[ 1 0 3]
[4 0 3] [-1 -3 7]

Each set of 9 numbers should only be in one bracket, but I didn't know how to do that on the computer. I know how to add and multiply matrices, but I can't even figure out what this problem is asking for.

2. Let your left matrix be S and your right matrix be T. Multiply both sides from the left by the inverse of S:
$\underbrace{{\color{blue}S^{-1}}S}_{I_{3}}A = {\color{blue}S^{-1}}T \: \: \Rightarrow \: \: A = S^{-1}T$

A matrix multiplied by its inverse will yield the identity matrix.
So find the inverse of S and multiply it with T to find A.

3. thanks so much, that's the exact help I needed!!