41/9*0,9; 27,2*2/17; 2 1/3*1,2; 0,6: 9/25; 8/21: 0,5; 3,5: 4 2/3.

4 1/9*0,9=37/9*9/10=37/10=3 7/10
27.2*2/17=135/10*2/17=135/5*1/17=27/17=1 10/17
2 1/3*1.2=7/3*1 2/10=7/3*12/10=7/1*4/10=7/1*2/5=14/5=2 4/5
0.6:9/25=6/10:9/25=6/10*25/9=2/2*5/3=5/3=1 2/3
8/21:0.5=8/21:5/10=8/21*10/5=8/21*2/1=16/21
3,5:4 2/3=3 5/10:14/3=35/10*3/14=5/10*3/2=3/4