We can rewrite this as
(2 * x^2/10) * (4/x^4)
x^2 4
2 -------- * ---------
10 x^4
we can cancel the x^2 by taking it out of the x^4 leaving
2 4
-------- * ---------
10 x^2
Multiply to get:
8
--------
10x^4
This can be reduced to:
4
--------
5x^2
or 4/5x^2