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