Heat and mass transfer

[ValeryOchkov]

In my student years, they said - "Handled the sopromat (Strength of materials) - you can fall in love! Passed the heat and mass transfer - you can get married!".
In the attachment and in the figure, the simplest problem from the problem book on heat and mass transfer, which I am currently working on.

Can you create more simple solution?

[AlanStevens · Accepted solution]

I would say that the following is simpler (it is even done in Prime Express)!

Alan