Equations with fractional exponents.

I have to solve a few equations that are similar to radial equations. I know how fractional exponents relate to square roots but I have something majorly wrong in my operations. I can't solve any of these. Here's one I could use help with. If I see enough steps I can easily apply it to the rest.

It's supposed to read 5x to the 5/3rd power.

I have a test tomorrow and I'm trying to get a grip on some of this stuff that I'm not understanding. Oddly enough I can handle quadratics with fractional exponents already, I just can't do this simpler version.