Respuesta :

First, let's factor both of these numbers.  

256x:

[tex] 2^{8} * x [/tex]

144x:

[tex] 3^{2} * 2^{4} * x [/tex]

Both of these numbers contain [tex] 2^{4} * x [/tex], so that would be the greatest common factor.  This could also be written as 16x.