You have to use the equation q=mcΔT and solve for T(final). T(final)=(q/mc)+T(initial) q=the amount of energy absorbed or released (in this case 868J) m=the mass of the sample (in this case 15.6g) c= the specific heat capacity of the substance (in this case 2.41 J/g°C) T(initial)=the initial temperature of the sample (in this case 21.5°C)
When you plug everything in, you should get 44.6°C. Therefore the final temperature of ethanol is 44.6°C
I hope this helps. Let me know if anything is unclear.