Hello,

Just a remark (or a correction) :

How are these differential equations ?I put this:

There is not even t in these expressions

This is how I see the problem.

Let's care about tank A first.

There are initially kg of X. So the ratio chemical/litre is

Hence if you remove a certain amount of litres, , there will be that will be removed.

Now, assuming that t is in minutes... We know that 5 litres are removed within 1 minutes.

So during t minutes, there are litres that are removed.

Can you see that if we consider the amount of chemical X removed during t, ?

So for tank A, there are kg of X that will be removed and go into tank B.

Similarly, there are kg of X that will be removed from tank B and that will go into tank A.

So your equations are :

(don't forget that there is initially a certain amount of chemical !)

and

do tell me if it looks incorrect to you