Which facts could be applied to simplify this expression? Check all that apply.

5 x + 3 y + (- x) + 6 z
A. To add like terms, add the coefficients, not the variables.
B. First add 5x + x.
C. The simplified expression is 4 x + 3 y + 6 z.
D. Only combine terms which contain the same variable.
E. The simplified expression is 5 x + 3 y + 6 z.