5 * 6 = 30
4 * 9 = 36
6 * 7 = 42
(10 + 4) * 6 = 10 * 6 + 4 * 6 = 60 + 24 = 84
(10 + 2) * 5 = 10 * 5 + 2 * 5 = 50 + 10 = 60
(10 + 3) * 6 = 10 * 6 + 3 * 6 = 60 + 18 = 78
17 * 4 = (10 + 7) * 4 = 10 * 4 + 7 * 4 = 40 + 28 = 68
11 * 6 = (10 + 1) * 6 = 10 * 6 + 1 * 6 = 60 + 6 = 66
21 * 3 = (20 + 1) * 3 = 20 * 3 + 1 * 3 = 60 + 3 = 63
(68 − 41) : 3 = 27 : 3 = 9
(23 + 17) : 5 = 40 : 5 = 8
(40 + 14) : 6 = 54 : 6 = 9