330 g of water at 55°c are poured into an 855 g aluminum container with an initial temperature of 10°
c. the specific heat of aluminum is what is the final temperature of the system, assuming no heat is exchanged with the surroundings?

The final temperature of the system is 32.5°
we know,  H = mcT 
where, H = Heat content of the body 
m = Mass,
c = Specific heat
T = Change in temperature
According to to the Principle of Calorimetry 

The net heat remains constant i.e. 
⇒ the heat given by water = heat accepted by the aluminum container.
⇒ 330 x 1 x (45 - T) = 855 x x (T - 10) 

⇒ 14,850 - 330T = 183.21T  - 1832 

⇒ - 513.21 T = - 16682

or T = 32.5°

The answer to the question is (a)