Question

Find the number of ordered pairs $(m,n)$ of integers that satisfy \[mn = 2m + 4n.\] $Find the number of ordered pairs (m,n) of integers that satisfy \[mn = 2m + 4n.\]$

Answer 1

There are four pairs (m,n) that work: (5,10), (6,6), (8,4), and (12,3).