Question 1132290
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I agree with the analysis by the tutor @MathLover1.


I only want to add that together with the pair (m,n) = (3,20), the pair (m,n) = (20,3) is also the solution.


It is clear from the fact that the original equation is symmetric relative "m" and "n".


So, the solutions are these 4 pairs  (m,n) = (5,6), (6,5), (3,20) and (20,3).
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