a)To find the GCF, list the factors and multiply those factors both numbers have in common. \(\displaystyle{6}\to{2}\cdot{3}\)

\(\displaystyle{15}{n}\to{3}\cdot{5}\cdot{n}\)

So, the GCF is: 3

b)To find the GCF, list the factors and multiply those factors both numbers have in common. \(\displaystyle{4}{m}\to{2}\cdot{2}\cdot{m}\)

\(\displaystyle{m}^{{2}}\to{m}\cdot{m}\)

So, the GCF is: m