=2x？ y+{2xy-9x？ y+6xy-4xy？ }=2x？ y+{8xy-9x？ y-4xy？ }

=2x？ y+8xy-9x？ y-4xy？ =8xy-7x？ y-4xy？

2. Let x be removed from the original polynomial. The part of +6x-6 is m, so there is m+x? +6x-6=2x？ -2x+3，

And then m=x? -8x+9, so the original polynomial is

m-(x？ +6x-6)=x？ -8x+9-(x？ +6x-6)=x？ -8x+9-x？ -6x+6

= 15- 14x；

Grandpa's age is three times that of Xiaohua's father and his age difference, and he is eight years younger. I don't understand who he is referring to. ...