28360:(u-52890)=40
28360/40=u-52890
709=u-52890
u=709+52890
u=53599
Ответ. u=53599
28 360 : (u -52 890)=40
u- 52 890 = 28 360 :40
u- 52 890 = 709
u = 709 + 52 890
u = 53 599