tolong dibantu nggeh secepatnya

jawabannya 14
[tex] \left[\begin{array}{ccc}3&1\\-1&p\end{array}\right] = \left[\begin{array}{ccc}p+r&3\\3&7\end{array}\right] - \left[\begin{array}{ccc}7&2\\4&3\end{array}\right] \left[\begin{array}{ccc}3&1\\-1&p\end{array}\right] = \left[\begin{array}{ccc}p+r-7&1\\-1&4\end{array}\right] p=4 p+r-7=3 (4)+r-7=3 r=3+7-4 =6 2p+r = 2(4)+6 =8+6=14 [/tex]