Problem:

A freshly brewed cup of coffee has temperature 95°C in a 20°C room. When its temperature is 78 °C, it is cooling at a rate of 1°C per minute. When does this occur? Approximate to three decimal places.

Here is my work, please verify if it is correct:

Therefore, the Coffee's temperature will be decreasing at 1 degree per minute after: 0.4934 minutes.