A pen cost rupees 3𝑥. The total cost of $5y$ such pens is ___ rupees

The correct option is A. $15xy$

Total cost of $5y$ pens $=$ cost of $1$ pen $\times 5y$

$=3x✕5y$

$=15xy$

Hence, the total cost of $5y$ such pens is $15xy$ rupees