200×(х+71)=54000;900×(16-с)=5400; 400×(х-12)=3600;

200×(х+71)=54000200*х+71*200=54000200х+14200=54000200х=54000-14200200х=39800х=39800/200х=199200*(199+71)=54000200*270=5400054000=54000;900×(16-с)=5400900*16-900*с=5400014400-900с=54000-900с=54000-14400-900с=39600-с=39600/900-с=44-х*(-1)=44*(-1)х=-44900*(16-(-44))=54000900*(16+44)=54000900*60=5400054000=54000;400×(х-12)=3600400*х-400*12=3600400х-4800=3600400х=3600+4800400х=8400х=8400/400х=21400*(21-12)=3600400*9=36003600=3600.