How do you use casio fx-991ms to solve Cramar's rule?

To use the Casio fx-991MS to solve a system of equations using Cramer's Rule, first, enter the coefficients of the equations into the calculator's matrix mode. Access the matrix function by pressing the 'MODE' button until you find the option for matrices, then select the appropriate size for your matrix. After entering the matrix, calculate the determinant using the 'Det' function. Finally, substitute the determinants of the modified matrices (where each column is replaced by the constants from the equations) into the Cramer's formulas to find the variable values.