150*х*3=1800, 12090-х=3090:30, а: 30=768+987, (х+240) * 3 - 360=540, 876+у+9869=78000

150*x*3=1800

150x=1800/3

x=600/150

x=4

12090-x=3090/30

12090-x=1030

x=12090-1030

x=11060

a/30=768+987

a/30=1755

a=1755*30

a=52650

(x+240) * 3-360=540

(x+240) = 540+360

x+240=900/3

x+240=300

x=60

876+у+9869=78000

876+у=78000-9869

876+у=68131

у=68131-876

у=67255