Which facts could be applied to simplify this expression? Check all that apply.
5 x + 3 y + (negative x) + 6 z

-To add like terms, add the coefficients, not the variables.

-First add 5x + x.

-The simplified expression is 4 x + 3 y + 6 z.

-Only combine terms which contain the same variable.

-The simplified expression is 5 x + 3 y + 6 z.