The water in your bathtub is getting cold. You currently have 36 liters at 31°C. What is the new temperature after you add 10 liters of 70°C hot water?

Question

The water in your bathtub is getting cold. You currently have 36 liters at 31°C. What is the new temperature after you add 10 liters of 70°C hot water?
Degrees Celsius are entered as degC.