3 5/16+(d-1 7/16)=9 1/16,
3 5/16 + d - 1 7/16 = 9 1/16,
d = 9 1/16 - 3 5/16 + 1 7/16,
d = (9 - 3 + 1) + (1/16 - 5/16 + 7/16),
d = 7 + 3/16.
d = 7 3/16,
проверка:
3 5/16 + (7 3/16 - 1 7/16) = 9 1/16,
3 5/16 + 5 12/16 = 9 1/16,
8 + 17/16 = 9 1/16,
8 + 1 1/16 = 9 1/16,
9 1/16 = 9 1/16