Ответ:\(-2,4a\cdot(-5b)=12ab\).\(14a-a-10b+7b=13a-3b\).\(x+(x-12)-(15+x)=x+x-12-15-x=x-27\).\(7(b+2)-5(b-2)=7b+14-5b+10=2b+24\).