Answer:
![(dT)/(dt)=k|T-M|](https://img.qammunity.org/2020/formulas/mathematics/college/ww0o1tjdpypulzp2m6bbe4tb6xuznpt9nc.png)
Explanation:
Given,
The rate of change in the temperature T of coffee at time t is proportional to the difference between the temperature M of the air at time t and the temperature of the coffee at time t,
i.e.
![(dT)/(dt)\propto |T-M|](https://img.qammunity.org/2020/formulas/mathematics/college/vi60ay1ogi4loix7k0fg125zdz01ujauik.png)
![\implies (dT)/(dt)=k|T-M|](https://img.qammunity.org/2020/formulas/mathematics/college/yng9v6s55kkkoy6r0n4j0w19i9jv9juys2.png)
Where, k is the constant of proportionality.