I was looking at the original question that was posted and answered by
I used the 7 and 4 as example and not looking for 39 per original
7+ 4 =11 and 7-4 = 3
We end up with 11 +3 = 14
A= 14/2 give use 7
B = how do you solve for B or 4 with out knowing anything about 3 or any other numbers ?