Stella is recording the temperature every day for five days on the first day it was 0 degrees and the second day was 3 degrees higher then the day before

First day temperature is 0 degree.

Second day temperature is 3 degree higher than first day's temperature.

In order to find the higher temperature we need to add increased temperature in previous day's temperature.

First day given temperature is 0 degree.

Three degree higher than 0 would be 0+3.

On adding 0 and 3 we would get 3.

Therefore, second day temperature would be 3 degrees.