Ответ:\(2a+(3a-8b)=2a+3a-8b=5a-8b\).\(-5b-(8a-5b)=-5b-8a+5b=-8a\).\(6x+(7-5x)=6x+7-5x=x+7\).\(-(4x-18)+18=-4x+18+18=-4x+36\).\((5-2b)-(7+10b)=5-2b-7-10b=-12b-2\).\(-(3c+5x)-(9c-6x)=-3c-5x-9c+6x=-12c+x\).\((2a-7y)-(5a-7y)=2a-7y-5a+7y=-3a\).