7/8+1/6-5/9
=25/24-5/9
=35/72
3/4+5/6-7/12
=19/12-7/12
=1
17/13-(4/13+2/18)
=17/13-49/117
=8/9
●7/8+1/6-5/9
=(21/24+4/24)-5/9
=25/24-5/9
=75/72-40/72
=35/72
●3/4+5/6-7/12
=9/12+10/12-7/12
=12/12
=1
●17/13-(4/13+2/18)
=(17/13-4/13)-1/9
=1-1/9
=8/9
7/8+1/6-5/9
=21/24+4/24-5/9
=25/24-5/9
=75/72-40/72
=35/72
3/4+5/6-7/12
=9/12+10/12-7/12
=19/12-7/12
=12/12
=1
17/13-(4/13+2/18)
=17/13-4/13-2/18
=1-2/18
=8/9