At T(0)=120.

By

Integrate both sides gives:

At T(0) we have T=120

......[1]

At T(2) we have 90:

....[2]

At T(4) we have 72:

....[3]

We have three equations to solve, [1], [2], and [3].

From [1], K=120-m

Sub into [2] and get

Can you finish?.