1) 1-4/9=9/9-4/9=5/9
2) 8 8/15 - 4 9/20= 128/15-89/20=512/60-267/60= 245/60= 49/12= 4 1/12
3) 4- 3 3/4=4-15/4=16/4-15/4= 1/4=0,25
4) 9 4/21-4 11/14= 193/21- 67/14= 386/42-201/42=185/42= 4 17/42
5)7 1/10-3 1/6=71/10-19/6= 213/30-95/30= 118/30=59/15=3 14/15
6)5 5/33 - 4 7/22= 170/33-95/22= 340/66-285/66=55/66=5/6