HI Alyssa,
I can expand a bit on the thorough explanation provided by James above. He notes three possible templates
1) H--R and S--T, G--T
This follows from the second rule. This template supposes that G comes before T. When that is the case, the rule tells us that "Roberto and Sonja must also perform earlier than Toshiro." Whenever G--T, we know from this rule that T must occur last, because H, R, G, and S all must occur before it.
2) H--S and T and R, T--G, T--R or S or both (this is the trickiest one)
This template acts as if it were not the case that G--T; that is, is supposes that T--G. This template also supposes that H--S and T (which is one of the two options from the third rule. If T--G, then we know from the second rule (from its contrapositive) that one of three possibilities is also the case: (1) S--T--G, (2) R--T--G, or (3) S and R--T--G. We also know from the third and first rules that either (1) H--S and T and R, or else (2) S and T--H--R.
3) S and T--H--R, T--G
This again supposes that T--G. However, instead of supposing H--S and T (one of the two options in the third rule), this template places both S and T
before H, or "S and T--H." Since we know that H--R from the first rule, we can plug this in as well, so this latter possibility more completely would be S and T--H--R. We also know that T--G in this template, though we don't know precisely when after T that G will occur (it might come before, after, or in between H and R).