What is the answer to the systems of equations x minus y equals 10 x plus y equals 4?
X - Y = 10
X + Y = 4
-------------------+ ( add them )
2X = 14
X = 7
----------find Y in one of the equations; top looks good
7 - Y = 10
- Y = 3
Y = - 3
---------------check both equations for consistency
7 - (- 3) = 10
7 + 3 = 10
10 = 10
------------checks in top
7 + (- 3) = 4
7 - 3 = 4
4 = 4
------------checks and is consistent
(7, - 3) ( the answer )