If the above statements are true, which of the following must also be true?

According to the question,
P was more effective than Q.
1. P > Q.
The effectiveness of R was less than that of S.
2. S > R.
T was the least effective brand tested.
3. T is least effective.
Q and R were equally effective.
4. Q = R.
The effectiveness of S was greater than that of Q.
5. S > Q.

from 1 and 5 ,
6. S/P > Q .
from 6 and 4 ,
7. S/P > Q = R .
from 7 and 3 ,
? S/P > Q = R > T

R was less effective than p.