1) 17,2*8,1+23,8*5,1-17,2*7,6-23,8*4,6=
=17,2(-7,6+8,1)+23,8(5,1-4,6)=17,2*0,5+23,8*0,5= 0,5(23,8+17,2) = 0,5*41= 20,5
Ответ: 20,5
2) (9+7/9)*(5+4/5)-3,3*2/5+2/9*(5+4/5)-6,7*2/5=
88/9*29/5-3,3*2/5+2/9*29/5-6,7*2/5=
=29/5(88/9+2/9)+2/5(-3,3-6,7)=
=29/5*10+2/5*(-11)= 53,6.