$A$ is invertible and $AX = B$. Which of these gives $X$?

Explanation

1. 01

   Multiply $AX = B$ on the left by $A^{-1}$: $A^{-1}AX = A^{-1}B$.

2. 02

   $A^{-1}A = I$ and $IX = X$, so $X = A^{-1}B$.