8 6/13 - (д + 9/13) =4 2/13 плииииииииз
8 6/13 - (д + 9/13) = 4 2/13; д + 9/13 = 8 6/13 - 4 2/13; д + 9/13 = 4 4/13; д = 4 4/13 - 9/13; д = 3 17/13 - 9/13; д = 3 8/13. Ответ: 3 8/13