title: How to calculate multiplicative inverse using reverse extended GCD algorithm
body: <p>I followed <a href="https://stackoverflow.com/questions/960190/how-to-calculate-the-inverse-key-matrix-in-hill-cipher-algorithm">How to calculate the inverse key matrix in Hill Cipher algorithm?</a> for the answer but couldn't get how to calculate 'x' in the problem given in the post using extended GCD algorithm</p>