Х-1 7/9=3 3/4-2 1/12
х-1 7/9=15/4-25/12
х-1 7/9=15*3/12-25/12
х-1 7/9=45/12-25/12
х-1 7/9=20/12=1 8/12=1 2/3
х=1 2/3+1 7/9
х=5/3+16/9
х=5*3/9+16/9
х=15/9+16/9
х=31/9
х=3 4/9
2 7/8-х=5,375-6 6/5
2 7/8-х=5375/1000-36/5
2 7/8-х=5375/1000-36*200/1000
2 7/8-х=5375/1000-7200/1000
2 7/8-х=-1825/1000=-1,825
х=-1,825-2 7/8
х=-1825/1000-23/8
х=-1825/1000-125*23/1000
х=-1825/1000-5750/1000
х=-7575/1000
х=-7,575