1) =38/10·(-3/4)+68/5 : 77/10= -19/10·3/2+68/5·10/17=-57/20+4·2=-57/20+8=
=-57/20+160/20=103/20=5 3/20=5,15
2) (4,3-7,85) :7,1=(43/10-785/100):71/10=(430/100-785/100)·10/71=
=(-355/100)·10/71=-5/10=-1/2=-0,5
3) =20/3·(-18/10)+165/10:(-11/4)=2·6+33/2·(-4/11)=12-3·2=6
4) =5/15-8/15=-3/15=-1/5=-0,2