differential equations problem..?

Question

at 2:00 pm a thermometer reading 80 deg F is taken outside where the air temperature is 20 deg F. At 2:03 pm, the temperature reading yielded by the thermometer is 42 deg F.. Later the thermometer is brought inside where the air temperature 80 deg F.. At 2:10 pm, the temperature reading is 71 deg F. When was the thermometer brought indoors?

oh yeah i 4got.. sorry..

Answer 1

I gave you some help with answering this not very long ago. You don't really want me to give you every line of the working that leads to the answer, do you?