28 целых 2/21-(14 целых 17/21+11 целых 8/21)

28 целых 2 / 21 - ( 14 целых 17 / 21 + 11 целых 8 / 21 )
1 ) 1-ый способ
( 2 8 * 21 + 2 ) / 21 - ( ( 14 * 21 + 17 ) / 21 + ( 11 * 21 + 8 ) / 21 ) = ( 588 + 2 ) / 21 - ( ( 294 + 17 ) / 21 + ( 231 + 8 ) / 21 ) = 590 / 21 - ( 311 / 21 + 239 / 21 ) = 590 / 21 - 311 / 21 - 239 / 21 = ( 590 - 311 - 239 ) / 21 = ( 279 - 239 ) / 21 = 40 / 21
28 + 2 / 21 - ( 14 + 17 / 21 + 11 + 8 / 21 ) = 28 + 2 / 21 - ( 25 + 17 / 21 + 8 / 21 ) = 28 + 2 / 21 - 25 - 17 / 21 - 8 / 21 = 3 + ( 2 - 17 - 8 ) / 21 = 3 - 23 / 21 = ( 21 * 3 - 23 ) / 21 = ( 63 - 23 ) / 21 = 40 / 21
ответ: 40 / 21