1/2a+3/8b-2/3a-b при а=3, b=4

упростим(1/2а-2/3а)+(3/8в-в)=(3/6а-4/6а)+(3/8в-8/8в)=-1/6а-5/8впри а=3,в=4-1/6*3-5/8*4=-3/6-20/8=-1/2-5/2=-6/2=-3ответ -3