Change the third equation by adding to it (-2) times the first equation. Give the abbreviation of the indicated operation.
{ x + 3y + 2z = 2
{ 2x - 3y - 5z = 1
{ 2x + 4y + 5z = 1
The transformed system is { x + 3y + 2z = 2
{ 2x - 3y - 5z = 1
{ _x + _y + _z = ___