combine like terms:
-3x+x
add:
-3x + x
NOTE: remember that x virtually equals 1
so -3*1+1=-1
hence, simplified x - 9 - 3x
= -2x-9
Helpful Information:
You should also note that when combining like terms, remember that the sign before the number goes w/ the number...for example: in the expression x-9-3x, x is positive b/c it doesn't have a negative sign or anything fancy before it. We can say 9 is negative or use it to subtract since it has a minus sign before it. -3x, 3 has a minus sign so we say it's negative.
x+-3x
1+-3*1
1+-3
=-2