1)
9 3/5×10/21=48/5×10/21=480/105=96/21=32/7
2)
3 11/12×9/94=47/12×9/94=423/1128=141/376
3)
1 5/7×6 1/8=12/7×49/8=588/56=294/28=147/14=21/2=10 1/2
4)
3 5/9×5 1/4=32/9×21/4=672/36=112/6=56/3=17 5/3
5)
1 13/15×5/8×2 2/7=28/15×5/8×16/7=140/120×16/7=7/6×16/7=112/42=56/21=8/3=2 2/3
6)
2 1/4×16/27×4 1/3=9/4×16/27×13/3=144/108×13/3=36/27×13/3=4/3×13/3=52/9=5 7/9