Many planets are so cold that they have temperatures which are negative. We'll use some fake planets in this part of the lesson.
On planet Velgar the temperature usually hits -40 degrees at night. On planet Ponktelitro the temperature at night is colder by 35 degrees. What is the usual night time temperature on planet Ponktelitro?
-40 - 35 = -75
-20 - 122 = -142