Solution to 13.

13. Either both the recording industry and the publishing industry provide useful services, or both Napster and web-publishing should be given legal latitude.

Doing the groupings we have:

Either (both the recording industry and the publishing industry provide useful services), or (both Napster and web-publishing should be given legal latitude).

We have two compound subjects. It should be clear what they are. The simple statements are:

R = The recoding industry provides useful services.

P = The rpublishing industry provides useful services.

N = Napster should be given legal latitude.

W = Web-publishing should be given legal latitude.

Substituting we get:

Either (both R and P), or (both N and W).

So clearly we have: