Question 722277
I know the answer is 38*83 = 3154
So the sum is 38+83 = 121
However I've been unable to derive it. Sorry.
I've got
(1) n1 = 10x + y and
(2) n2 = 10y + x 
Therefore the sum is
(3) n1 + n2 = 11x + 11y or
(4) sum = 11(x+y)
But I can't come up with 3 and 8 for x and y.
Nor can I solve 
(5) n1*n2 = 3154
We know that n1 (or n2) has to be greater than 32 in order to get a second two digit number for the product.
Maybe we can say both are greater than 32 which means x or y has to be 3, then try 33*33, 34*43, 35*53, 36*63, 37*73, 38*83, 39*93. Indeed
the answer appear, but mathematician can't accept trial and error. There's got to be a better way.