[plzhelpmee]

What was the original temperature of 160.2 grams of water if placing a 31.52-g piece of aluminum with specific heat of 0.897J/g°C at 100.0°C warms the water up to 25.0°C .
I don´t get how this works, and here is my work, but it doesnt work.  The answer given was 21.8°C , but i am not sure how to get that.

M x C x (Tf - Ti ) = - M x C x (Tf - Ti)
31.52g x 0.897J/g°C x (Tf-100°C) = 160.2g x 4.18J/g°C x (25°C-Ti)

[mikasaur]

Hmmm, your work looks good. What answer did you get? 28.1? It's possible the answer key transposed the 8 and the 1.

Is this from a textbook or from a teacher's assignment?