Answer:
Because a drop in temperature means decrease in temperature therefore, we take an integer with negative sign and added to previous temperature.
Explanation:
Drop in temperature means decrease in the temperature .When the temperature decreases then we take decrease value of temperature in negative integer. Because decrease means the temperature fall down .Hence , the decrease in temperature measure with negative sign .
For example, if we take temperature T= 70°C.
If the temperature decreases by 5°c then the temperature
Decrease in temperature=-5°C
Hence, the temperature T= 70+(-5)=65°C.
Therefore , from example we can say that when temperature decreases by some value in integer . Then ,we get final temperature obtained by adding drop in temperature ( negative integer ) in previous value of the temperature.