Well I'm back again after failing Calculus again....

And It just makes me and wanna shoot myself for not being able to solve this problem even though since I'm taking the same class three times in a row but I still can't solve this argh

I ended up with ((x^2)/2)/((x^3/2)/(3/2)) - (6x)/((x^3/2)/(3/2)) but I know that my process is incorrect.

How do I solve this?