10m^4n(-2mn^3+3n)

To simplify the expression 10m^4n(-2mn^3 + 3n), we use the distributive property to multiply each term in the first expression (10m^4n) by each term in the second expression (-2mn^3 + 3n).

First, let's multiply 10m^4n by -2mn^3:
10m^4n * -2mn^3 = -20m^5n^4

Next, let's multiply 10m^4n by 3n:
10m^4n * 3n = 30m^4n^2

Now, we can combine the two simplified terms:
-20m^5n^4 + 30m^4n^2

So the simplified expression is -20m^5n^4 + 30m^4n^2.