-5nm3 X -4m2n4. Show your work please!

Simplify the following:
-5 (-4) n m^3 m^2 n^4

-5 n m^3 (-4) m^2 n^4 = -5 n^(1+4) m^(3+2) (-4):
-5 (-4) n^(1+4) m^(3+2)

3+2 = 5:
-5 (-4) n^(1+4) m^5

1+4 = 5:
-5 (-4) n^5 m^5

-5 (-4) = 20:
Answer: |20 n^5 m^5