Mathematics - Algebra - Systems of Equations - Solving systems by elimination - Add to Eliminate

Show: 'x+y=10' and 'x-y=4'. 'What happens if we ADD these equations?' x+y+x-y=10+4 → 2x=14 → x=7! The y-terms CANCELLED! Then y=3. Do 3 systems where adding/subtracting directly eliminates a variable. Students see the power of the method.