Question

the temperature of a room is 12 pieces and out and outside temperature is 36 degree Celsius the temperature of this room increased at the rate of 4 degree Celsius for 30 minutes ​

Answer 1

If it's -20 degrees outside and it decreases 3 degrees what

temperature is it?  I know the answer is -23 degrees but it seems like

it should be -17 degrees.  When do you have to change the sign into

addition?