求几道初一下的先化简再求值的数学题,

(X-3)(X^2+6X+9)-(X+3)(x^2+2x-15）,x=12x-(x+3y)-(-x-y)-(x-y),x=5,y=9-2(3x+z)-(-6x)+(-5y+3z),x=10,y=20(2x2-3xy+4y2)+(x2+2xy-3y2）,x=12,y=154x2-[7x2-5x-3(1-2x+x2)],x=42x+2y-[3x-2(x-y)] ,x=6,y=1 /2&n...