[tex]Answer: 3a^2b(b-25am^{a-1}).[/tex]
Step-by-step explanation:
[tex]\displaystyle\\3a^2b^2m-75a^3bm^a=3a^2bm*b-3a^2bm*25am^{a-1}\\3a^2bm*b-3a^2bm*25am^{a-1}=3a^2bm(b-25am^{a-1}).[/tex]