p^2+3pq+6-8p^2+pq
=(p^2-8p^)+(3pq+pq)+6
=-7p^2+4pq+6
5x^4+3x^2y-10-3x^2y+x^4-1
=(5x^4+x^4)+(3x^2y-3x^2y)-(10+1)
=5x^4-11
(7y-3z)-(8y-5z)
=7y-3z-8y+5z
=(7y-8y)+(5z-3z)
=-y+2z
-(a^5-6b)-(-7+3b)
=-a^5+6b+7-3b
=-a^5+(6b-3b)+7
=-a^5+3b+7
2(2a^2+9b)+3(-5a^2-4b)
=4a^2+18b-15a^2-12b
=(4a^2-15a^2)+(18b-12b)
=-11a^2+6b
-3(2x^2-xy)+4(x^2+xy-6)
=-6x^2+3xy+4x^2+4xy-24
=(-6x^2+4x^2)+(3xy+4xy)-24
=-2x^2+7xy-24