x+(x-2)+(x-4)+(x-6)=216
x+x-2+(x-4)+(x-6)=216
2x-2+(x-4)+(x-6)=216
2x-2+x-4+(x-6)=216
3x-6+(x-6)=216
3x-6+x-6=216
4x-12=216
4x=228
x=57