Ответ:\(7(4a+6)-12a=28a+42-12a=16a+42\).\(8x-4(16-2x)=8x-64+8x=16x-64\).\(1.7(a-4)+0.6(6-2a)=1.7a-6.8+3.6-1.2a=0.5a-3.2\).