9514 1404 393
Answer:
476 +598 = 1074
Explanation:
In order for the sum to be smallest, the two most-significant digits must be the smallest possible. That is, they must be 4 and 5.
The two least-significant digits must be even. The remaining even digits are 6 and 8. Then the tens digits are the digits left over: 7 and 9.
Possible sums are ...
476 +598 = 1074
478 +596 = 1074
496 +578 = 1074
498 +576 = 1074
The sum is 1074.