Call the two-digit number : ab
The new number formed : ba
We have : 10a + b + 10b + a = 143
11a + 11b = 143
a+b = 143 : 11 = 13
So, we have a few combinations for a and b : (4;9) , (5;8) , (6;7) , (7;6) , (8;5) , (9;4)
Out of all these, only 76 is the satisfied number, as the new number formed is 67, and 76 + 67 = 143 ; 76 - 67 = 9
