It was 13 degrees Celsius yesterday, but the temperature changed by -18.6 degrees overnight. What is the temperature now?

To find the current temperature, we need to subtract 18.6 degrees from yesterday's temperature.

Temperature now = 13 degrees Celsius - 18.6 degrees Celsius
Temperature now = -5.6 degrees Celsius

To find the current temperature, we need to subtract the change in temperature from the temperature yesterday.

Temperature yesterday: 13 degrees Celsius
Change in temperature: -18.6 degrees Celsius

To find the current temperature, we can calculate:

Current temperature = Temperature yesterday + Change in temperature

Current temperature = 13 degrees Celsius + (-18.6) degrees Celsius

Adding the values, we get:

Current temperature = 13 degrees Celsius - 18.6 degrees Celsius

Calculating, we find:

Current temperature = -5.6 degrees Celsius

Therefore, the current temperature is -5.6 degrees Celsius.