The first two branches are T (0.7) and T' (0.3). The next two branches (that each go from T and T') are N and N'. The N branch from T has a probability 0.2. The N' branch from T has a probability of 0.8.
The N and N' branches from T' can be found from the fact that the total probability of N is 0.35. You will probbaly need to work this out for the later parts of the quesiton.