The diagram shows:
Assuming that the text meant to say that
QR ≅ RS
If RS= 12, then QR=12
Point S divides segment RT into two, segments RS and ST
This means that RT=RS+ST
Then we can calculate ST as
[tex]\begin{gathered} RT=RS+ST \\ ST=RT-RS \\ ST=30-12 \\ ST=18 \end{gathered}[/tex]
To calculate segment QS, you have to add QR and RS
[tex]\begin{gathered} QS=QR+RS \\ QS=12+12 \\ QS=24 \end{gathered}[/tex]
To calculate QT, you can add QS and ST
[tex]\begin{gathered} QT=QS+ST \\ QT=24+18 \\ QT=42 \end{gathered}[/tex]
