#### Answer

$$6m^{4}-2m^{3}-7m^{2}-4m$$

#### Work Step by Step

Initial equation:
$$(6m^{4}-3m^{2}+m)-(2m^{3}+5m^{2}+4m)+(m^{3}-m)$$ Begin by distributing the signs located between the sets of parenthesis, the $-$ going to the second set, and the $+$ going to the third set:
$$6m^{4}-3m^{2}+m-2m^{3}-5m^{2}-4m+m^{3}-m$$ Then combine like terms:
$$6m^{4}-2m^{3}-7m^{2}-4m$$