Question 391907
If (a,b) and (c,d) exhibit direct variation, then {{{b/a = d/c}}}.
If (a,b) and (c,d) exhibit inverse variation, then ab = cd. 
Since the quotients n/m above don't give a constant value, n and m don't vary directly.  Also, the products mn don't give a constant value, so n and m don't vary inversely. Therefore the answer is NEITHER.