(580:x-25)*90+490=850
52200 - 2250+490=850
x
52200 = 850+1760
х
52200 = 2610
х=20
(580:x-25)*90+490=850 (580:x-25)*90=850-490 (580:x-25)*90=360 580:x-25=360/90 580:x-25=4 580:x=25+4 580:x =29 х=580/29 х=20
поблагодари))))))