Quick matrix transpose proof help

[bossman007]

Homework Statement

let transpose of A be noted by A`

Show that if the matrix product AB is permitted, then so is the product B`A`, where

B`A`=(AB)`

Homework Equations

$C_{ij}=ƩA_{ik} B_{kj}$ where summing from k=1 to m

$A`_{ij} = A_{ji}$

The Attempt at a Solution

It wants me to use the relevant equations to prove this, but I am not sure where to start, seeing as the most I have done with matrices so far is add and multiply them

 

[haruspex]

What properties of matrices A and B do you think are needed for the multiplication AB to be a permitted operation?