You are correct! You understood that the surroundings became cooler and therefore the process was endothermic...the heat flow was from the surroundings to the system. You calculated the amount of heat "q" for the surroundings by the following calculation and then changed the sign because the system is gaining heat. You then realized that this heat was for 0.105 moles and converted your answer to J/1 mole by dividing your answer by 0.105.

4.184 J/gdeg x 261.6 g_{(the total mass)} x (-3.5 deg) = -3830 J