I'm really struggling with this one. In regards to which steps I've taken to solve it on my own, I got nothing but some pathetic attempts to isolate [ S] or play around with the formula. I'm spectacularly bad at this type of chemistry. I've read up on it but I still don't get it.
I'll try to translate it to the best of my ability.
The link between the substrate concentration [ S] and the initial velocity V0 is given by the following equation:
V0 = Vmax*[ S]/Km+[ S]
Indicate the amount of [ S] (in relation to Km) in which V0 = 66,67% of the maximal velocity.