(3w^2 / 2c^3d) - (5cx / 8d^3k^20)
So we need the bottoms to be the same.
The left bottom is missing 4d^2k^20, so:
( (3w^2 * 4d^2k^20) / (2c^3d * 4d^2k^20) ) - (5cx / 8d^3k^20)
(12d^2k^20w^2 / 8c^3d^3k^20) - (5cx / 8d^3k^20)
The right bottom is missing c^3, so:
(12d^2k^20w^2 / 8c^3d^3k^20) - (5c^4x / 8c^3d^3k^20)
The bottoms are the same, so now we can do this:
(12d^2k^20w^2 - 5c^4x) / 8c^3d^3k^20
Is there anything to factor on the top?
12 and 5 have nothing to factor.
The left top has only d, k, and w and the right top has only c and x, so there's nothing to factor out on the top.
If there's nothing to factor out of the left and right parts on the top, there's nothing we can cancel between the top and bottom.
We could turn the top into (2sqrt(3)dk^10w - sqrt(5x)c^2)(2sqrt(3)dk^10w + sqrt(5x)c^2), but that still wouldn't give us anything to cancel with the bottom.
Answer: (12d^2k^20w^2 - 5c^4x) / 8c^3d^3k^20