add logic for use case ie (3 - 1 + 2 = :: 4) for when user switches method. Break through commit
add logic for use case ie (3 - 1 + 2 = :: 4) for when user switches method. Break through commit

wwwfreedom/FreeCodeCamp,wwwfreedom/FreeCodeCamp,wwwfreedom/FreeCodeCamp