Find the missing number.

Find the missing number. ?, 12, 55; 9, 7, 4; 61, 6, 31

Find the missing number. 13, 11, 31 19, 9, 17 23, ?, 25

Find the missing number. 3 2 = 7, 5 4 = 23, 7 6 = 79, 10 9 = ?