1: (1/7+1/5)
2) 1 : (1/3 + 1/5)
3) (10*16):(10+16)=160:26=6 4/26 = 6 2/13 д.
562 - (у + 116) = 243
у + 116 = 562 - 243
у + 116 = 319
у = 319 - 116
у = 203
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Проверка:
562 - (203 + 116) = 243
562 - 319 = 243
243 = 243