Energy = mass * SHC * temp change
Temp change = energy/SHC * mass
42kJ - 42000J (convert kJ to J as energy is counted as J/kg)
Temp change = 42000/4200*10
= 1C
So it goes up by 1C thus the final temperature would be 26C
Or a more logical way to think of it would be that if it takes 4200J to heat up 1kg of water by 1C (SHC is 4200J/kgC) it would take ten times the amount of energy to heat up 10kg of water by 1C hence it takes 42000J.