10-(6x-8x²+2)-2(5x²+4x-1)
=10-6x+8x²-2-10x²-8x+2
=8x²-10x²-6x-8x+2-2+10
=-2x²-14x+10
=-2*(-2)²-14*(-2)+10
=-2*4+28+10
=30
-3a+｛2b-(a-b)+a｝+(6a-b)
=-3a+2b-(a-b)+a+6a-b
=-3a+2b-a+b+a+6a-b
=-3a-a+a+6a+2b+b-b
=3a+2b