How do you simplify #(8mn^2)/(4m)#?
You can see clearly that you have
Now, you can divide
The final answer, then, will be
Another possible way to adress this problem is by factoring the elements that appear up and down your function, as shown:
And now cancel the ones that appear exactly the same up and down because they do not change the value of your function, as they both multiply and divide by the same number: