A Camper Is About to Drink His Morning Coffee $75 ^ { \circ } \mathrm { C }$

A camper is about to drink his morning coffee. He pours 400 grams of coffee, initially at $75 ^ { \circ } \mathrm { C }$ into a 250-g aluminum cup, initially at $16 ^ { \circ } \mathrm { C }$ What is the equilibrium temperature of the coffee-cup system, assuming no heat is lost to the surroundings? The specific heat of aluminum is 900 $\mathrm { J } / \mathrm { kg } \cdot \mathrm { K }$ and the specific heat of coffee is essentially the same as that of water, which is $4186 \mathrm {~J} / \mathrm { kg } \cdot \mathrm { K }$

A) $62 ^ { \circ } \mathrm { C }$
B) $65 ^ { \circ } \mathrm { C }$
C) $68 ^ { \circ } \mathrm { C }$
D) $45 ^ { \circ } \mathrm { C }$
E) $71 ^ { \circ } \mathrm { C }$