Fill in the blank with a constant, so that the resulting expression can be factored as the product of two linear factors.
3mn - 6m + 15n + ___
3mn - 6m + 15n + a
mn - 2m + 5n + a/3
(m+5)(n-2) = mn - 2m + 5n - 10
mn - 2m + 5n + a/3 = mn - 2m + 5n - 10
a = -30
=^._.^=
