* added script for solving system of linear equations in two variables
* implemented all the suggested changes
* changed RuntimeError to ValueError
* Update matrix/system_of_linear_equation_in_2_variables.py
* Update matrix/system_of_linear_equation_in_2_variables.py
* Update and rename system_of_linear_equation_in_2_variables.py to cramers_rule_2x2.py
Co-authored-by: Christian Clauss <cclauss@me.com>