Answer:
The expression will be T=7r
Explanation:
From equation S=dT/dr, we can solve this equation by integrating it and usig the values 25C and 18C for T and 2 and 1 for the radius. The solution to the integration will result in the value for S. For this example, it will be 7. Therefore, the main expression will be T= 7r in which the temperature is in fuction of the radius between the spheres.