Process energy required
1) raise the temperature to 75.0 °C 628 J
2) evaporate the liquid at 75.0°C 15.6 KJ = 15,600 J
3) raise the temperature to ? 712 J
Total energy: 628 J + 15,600 J + 712 J = 16,940 J
As you must have realized the clue to do the problem correctly is to convert all the energy values to joules, because you cant not add up joules with kilo joules.
Answer: 16,940 J