[tex]2+2+x+10+x-2+9=x\\2+2+x+10+x-2+9 -x=0\\(2+2+10-2+9)+(x+x-x)=0\\21+x=0\\x=-21[/tex]
ANSWER: ? = -21
P/s: ? = x < let ? is x >
ok done. Thank to me :>
