9514 1404 393
Answer:
C) 7
Step-by-step explanation:
We have ...
TS +SR = 19
SR +RQ = 13
Adding these two equations together, we have ...
TS +2·SR +RQ = 19 +13 = 32
We also have ...
TS +SR +RQ = 25
Subtracting this from the equation above, we have ...
(TS +2·SR +RQ) -(TS +SR +RQ) = 32 -25
SR = 7