1)1/3-1/4=1/(12/4-1/4)=1/(11/4)=1*4/11=4/11
2-4/11=22/11-4/11=18/11
1/(18/11)=1*11/18=11/18
1-11/18=18/18-11/18=7/18
2)1/3-1/3=1/(9/3-1/3)=1/(8/3)=1*3/8=3/8
3-3/8=24/8-3/8=21/8
1/(21/8)=1*8/21=8/21
3-8/21=63/21-8/21=55/21=2 целых 13/21
3)1/1-1/3=1/(3/3-1/3)=1/(2/3)=1*3/2=3/2
1+3/2=2/2+3/2=5/2
1/(5/2)=1*2/5=2/5
1-2/5=5/5-2/5=3/5
1/(3/5)=1*5/3=5/3
1+5/3=3/3+5/3=8/3=2 целых 2/3