3. 12 - 2 - 3, 12 - 2 - 7, 13 - 3 - 5, 13 - 3 - 6, 8 + 7 - 10, 6 + 8 - 10

Вычисления:

\( 12 - 2 - 3 = 10 - 3 = 7 \)

\( 12 - 2 - 7 = 10 - 7 = 3 \)

\( 13 - 3 - 5 = 10 - 5 = 5 \)

\( 13 - 3 - 6 = 10 - 6 = 4 \)

\( 8 + 7 - 10 = 15 - 10 = 5 \)

\( 6 + 8 - 10 = 14 - 10 = 4 \)

Ответ: 7, 3, 5, 4, 5, 4.