12000*x=24000 12000*x=80*30 80000: y=4000-2000 (500000-100000): b=80

12001×x=24000
x=24000:12000
x=2000

12000×x=80×30
12000×x=2400
x=2400:12000
x=0,02

80000:y=4000-2000
80000:y=2000
y=80000:2000
y=40

(500000-100000):b=80
500000-100000=400000
400000:b=80
b=400000:80
b=5000
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