64 : 4 = (40 + 24) : 4 = 40 : 4 + 24 : 4 = 10 + 6 = 16
 
7 * 12 = 7 * (10 + 2) = 7 * 10 + 7 * 2 = 70 + 14 = 84
 
50 : 2 = (30 + 20) : 2 = 30 : 2 + 20 : 2 = 15 + 10 = 25
 
39 : 3 = (30 + 9) : 3 = 30 : 3 + 9 : 3 = 10 + 3 = 13