How to solve

Calculate the complexity of Gaussian Elimination Algorithm. $($i$.$e$.,$ find the number of basic operations that you have to perform to find an echelon form of an $nn$ matrix using the GEA.$)$

$($Hint: You must have noticed that for each row in a particular step, we perform $1$ division and many multiplications and subtractions, depending on the order of the matrix. Let us assume that division is 'difficult' than multiplication and even more 'difficult' than subtraction. So let us consider that a combination of multiplication and subtraction is as difficult as a division. Hence, consider $1$ division as $1$ basic operation and $1$ combination of multiplication$-$subtraction as $1$ basic operation$)$