Can someone clarify where I'm going wrong with this?

Question

Kw for pure water is 1.2 x 10-15 at 5°C. The pH of pure water at 5°C?

I thought Kw=[H3O][OH]...

I've tried a few different things, but none seem to work.

Thanks!

Answer 1

I figured it out. :)

Wolframalpha Failed to understand what i meant and have me the wrong answer even though I did everything correctly.