А) х+(1200-900)=1500
х=(1200-900)
х=300
х=1500-300
х=1200
б) (50•30):у=15
(50•30)=1500
х=1500:15
х=100
в) с:(1200:2)=3
с=(1200:2)
с=600
с=600•3
с=1800
1.
=10 7/10+х+2/5=107/10+х+4/10=111/10+х.
111/10+9/10=120/10=12
111/10+2/5=111/10+4/10=115/10=11 5/10=
=11 1/2
2.
25 6/7-х-5/14=181/7-х-5/14=362/14-5/14-х=
=357/14-х
357/14-5 1/2=357/14-11/2=357/14-77/14=
=280/14=20
357/14-3/4=714/28-21/28=686/28=24 1/2
3.
х+3/5-17/30=х+18/30-17/30=х+1/30
6+1/30=6 1/30
7/10+1/30=21/30+1/30=22/30=11/15