The temperature on Monday is -4 degrees Celsius. On Tuesday , it is 13 degrees colder. What is the temperature on Tuesday?
The temperature on Tuesday is -4 degrees Celsius - 13 degrees Celsius = -17 degrees Celsius. Answer: \boxed{-17}.
To find the temperature on Tuesday, we need to subtract 13 degrees from the temperature on Monday.
Given that the temperature on Monday is -4 degrees Celsius, we subtract 13 from -4:
-4 - 13 = -17
Therefore, the temperature on Tuesday is -17 degrees Celsius.