1/12+1/6,3/4+1/6,1/2+3/5,2/11+1/3,2/3-3/4,1/4+4/5,1/2+1/4-1/8.

1/12+1/6=1/12+2/12=3/12=1/4

3/4+1/6=9/12+2/12=11/12

1/2+3/5=5/10+6/10=11/10=1  1/10

2/11+1/3=6/33+11/33=17/33

2/3-3/4=8/12-6/12=2/12=1/6

1/4+4/5=5/20+16/20=21/20=1  1/20

1/2+1/4-1/8=4/8+2/8-1/8=5/8

ВСЁ!