Matrix multiplication

In a school event, the number of participants for Art, Music and Drama from Classes X and Y is
$P = \begin{bmatrix} 12 & 8 & 10 \\9 & 7 & 11 \end{bmatrix}$, where the first row is Class X and the second row is Class Y.

The registration fees (in dollars) for Art, Music and Drama are
$R = \begin{bmatrix} 5 & 7 & 9 \end{bmatrix}$.

Using matrix multiplication, find the total registration fees collected from Class X.