(1,2-1,8в+3)(-2)-5(1,2+1,86-1,3)=
(1,2-1,8в+3)(-2)-5(1,2+1,86-1,3)=-2,4+3,6b-6-6+9,3-6,5=-11,6+3,6b
1)1.2+3=4.2 2)(4.2-1.8в)(-2)=-4.2-1.8в)*2 3)(4.2-1.8в)*2=8.4-3.6в 4)-(8.4-3.6в)=-8.4+3.6в 5)1.2+1.86=3.06 6)3.06-1.3=1.76 7)5*1.76=8.8 8)-8.4-8.8=-17.2 Ответ:-17.2+3.6в