х+(1200-900)=1500
х+300=1500
х=1500-300
х=1200
(50*30):у=15
1500:у=15
у=1500:15
у=100
с:(1200:2)=3
с:600=3
с=600*3
с=1800
х+(1200-900)=1500
х+300=1500
х=1500-300
х=1200
(50*30):у=15
1500:у=15
у=1500:15
у=100
с:(1200:2)=3
с:600=3
с=600*3
с=1800