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

200 * (х+71) = 54000

200*х+71*200=54000

200 х+14200=54000

200 х=54000-14200

200 х=39800

х=39800/200

х=199

200 * (199+71) = 54000

200*270=54000

54000=54000;

900 * (16-с) = 5400

900*16-900*с=54000

14400-900 с=54000

-900 с=54000-14400

-900 с=39600

-с=39600/900

-с=44

-х * (-1) = 44 * (-1)

х=-44

900 * (16 - (-44)) = 54000

900 * (16+44) = 54000

900*60=54000

54000=54000;

400 * (х-12) = 3600

400*х-400*12=3600

400 х-4800=3600

400 х=3600+4800

400 х=8400

х=8400/400

х=21

400 * (21-12) = 3600

400*9=3600

3600=3600.