Matrix multiplication

In a stationery shop, a pen costs \$2 and a notebook costs \$3.50. In another shop, the price of a pen is \$0.40 less and the price of a notebook is \$0.80 more.

The prices in the two shops are represented by the matrix
$Q = \begin{bmatrix}2 & 3.5 \\1.6 & 4.3\end{bmatrix}.$

A customer buys 5 pens and 4 notebooks. Represent this as a matrix $P$ and evaluate the matrix product $PQ$.