уравнения (x+20)×45=3105 ; 57×(500-x)=11457

х+20=3105:45=69х=69-20х=49500-х=11457:57=201х=500-201х=299

(х+20)*45=3105х+20=3105/45х+20=69х=69-20х=49-------------------------проверка(49+20)*45=31053105=310557*(500-х)=11457500-х=11457/57500-х=201х=500-201х=299---------------------------проверка57*(500-299)=1145711457=11457