Answer:
(Thermometer B reading - Thermometer A reading)
Explanation:
The thermometer reading aren't given in the question.
However, hypothetically.
The difference between two temperature values (morning and evening values) would be :
Temperature in the evening - morning temperature
Therefore,
If ;
Thermometer A reading = morning temperature
Thermometer B reading = evening temperature
Difference in the temperature :
(Thermometer B reading - Thermometer A reading)