Question 1077199
Substitution: use when one variable is expressed in terms of another.  Not so good if fractional.
Elimination: by far the most common and reliable.  Use to make the equations such that adding them causes one variable to disappear.  It can be time-consuming, but usually any other method would be, too.
Graphing: Can be useful, but hand made graphs are difficult to interpret, especially when the intersection point is not an integer.