2400: x=2, x=2400:2. X=1200, 2400:1200=2. 2=2-верно. A+21000=100000 ,a=100000-21000 , a= 79000, 79000+21000=100000, 100000=100000-верно. y*4=560000, y=560000:4, y=140000, 140000*4=560000, 560000=560000-верно. b-47000=100000, b=100000+47000, b=147000 , 147000-47000=100000. 100000=100000-верно