The specific heat capacity of ethanol is 2.46 joules per gram.
Now, we may use the equation:
Energy = mass * specific heat capacity * change in temperature
Here we may substitute:
mass = density * volume
Energy = density * volume * specific heat capacity * change in temperature
720 = 0.789 * 35 * 2.46 * ΔT
ΔT = 10.6
The final temperature will be
20 + 10.6
= 30.6 °C