Explicație pas cu pas:
1-4/7=7/7-4/7=3/7
1-7/8=8/8-7/8=1/8
1-2/9=9/9-2/9=7/9
1-3/4=4/4-3/4=1/4
3-1/2=6/2-1/2=5/2=2 1/2
2-3/4=8/4-3/4=5/4=1 1/4
1-4/15=15/15-4/15=11/15
1-3/7=7/7-3/7=4/7
