X*60-9000=54000 1360-x+500=1200 5400: x-810=90 15*×-15000=9000

54000+9000=63000 
x=63000/60
x=1050

1360-x+500=1200
x=1200-500
x=700
x=1360-700
x=660

5400/x-810=90
x=90+810=900
x=5400/900
x=6

15*x-15000=9000
x=15000+9000
x=24000
x=24000/15
x=1600