Since, Profit = Revenue – cost

Requirement is, profit > 0

\[C\left( x \right)\text{ }=\text{ }26,000\text{ }+\text{ }30\text{ }x;\]

where x is number of cassettes

\[\begin{array}{*{35}{l}}

\Rightarrow ~Profit\text{ }=\text{ }43x\text{ }\text{ }\left( 26,000\text{ }+\text{ }30x \right)\text{ }>\text{ }0  \\

\Rightarrow ~13x\text{ }\text{ }26,000\text{ }>\text{ }0  \\

\Rightarrow ~13x\text{ }>\text{ }26000  \\

\Rightarrow ~x\text{ }>\text{ }2000  \\

\end{array}\]

Therefore, the company should sell more than 2000 cassettes to realise profit.