How would I calculate this?

Question

30.0 mL of pure water at 280. K is mixed with 50.0 mL of pure water at 307 K. What is the final temperature of the mixture?

Answer 1

heat lost by warm water + heat gained by cool water = 0

[mass warm water x specific heat water x (Tfinal-Tinitial)] + [mass cool water x specific heat H2O x (Tfinal-Tinitial)] = 0
Substitute and solve for Tf.