Question 25
There were four couples who came to the celebration event. Among four wives (namely A, B, C, D), A has eaten 5 cakes, B has eaten 1 cake, C has eaten 3 cakes and D has eaten 4 cakes. Among four husbands (namely I, M, S, O), I have eaten cakes 4 times which his wife has eaten, M has eaten cakes 3 times which his wife has eaten, S has eaten cakes 2 times which his wife has eaten, and O has eaten as many cakes as his wife has eaten. If the total number of cakes the four couples ate was 39, what is the number of cakes did S and his wife eat in total?