This is a simples JS code that calculates the Cramer rule up to 4 variables. The simple html makes it easy and direct to know were to place the values. Sadly it only supports integers. As result we have: -The determinant from the coeficient matrix; -The determinant from the alpha matrix; -The determinant from the beta matrix; -The determinat from the gamma matrix (if three coeficients); -The determinant from the theta matrix (if four coeficients); -Tha values of alpha, beta, gamma, and theta.