Answer:
[tex]m^4n^{-3}[/tex]
Step-by-step explanation:
Exponent rules. When multiplying exponents with like bases, you keep the base and add the exponents. So:
[tex]mn^2 \times m^2n^{-4} \times mn^{-1}\\=m^{(1+2+1)}n^{(2+[-4]+[-1])}\\=m^4n^{-3}[/tex]