-2,3*4c=
-0,9b*(-0,6)=
-5a*3,6b=
-8x*(-0,5y)*0,6m=
-8/21z*(-m)*7/24=
2 2/7m*(-21/64n)=

-2,3*4c=-9,2c-0.9b*(-0.6)=0,54b-5a*3.6b=-18ab-8x*(-0.5y)*0.6m=2,4xym-8/21z*(-m)*7/24=1/9zm2 2/7m*(-24/64n)=-6/7mn