(6,8-5 5/9):(2 13/30-2 1/12)*3,6=12цел4/5
1.)6,8-5цел5/9=6цел8/10-5цел5/9=6цел72/90-5цел50/90=1цел22/90=1цел11/45
2.)2цел13/30-2цел1/12=2цел26/60-2цел5/60=21/60=7/20
3.)1цел11/45:7/20=56/45:7/20=56×20/45×7= =8×4/9×1=32/9=3цел5/9
4.)3цел5/9×3,6=3цел5/9×3цел6/10= =32/9×36/10=32×36/9×10=16×4/1×5=64/5= =12цел4/5