The selling prices of a chemistry book, a physics book, and an economics book are respectively  given as  Rs. $80$, Rs. $60$ and Rs. $40 .$

The total amount of money that will be received from the sale of all these books can be erepresented in the form of a matrix as :

$12\left[\begin{array}{lll}10 & 8 & 10\end{array}\right]\left[\begin{array}{l}80 \\ 60 \\ 40\end{array}\right]$

$=12[10 \times 80+8 \times 60+10 \times 40]$

$=12(800+480+400)$

$=12(1680)$

$=20160$

Thus, the bookshop will receive Rs. $20160$ from the sale of all these books.