Concert Ticket Sales System

In a town, there are two types of tickets for a concert: regular tickets and VIP tickets. The following system of linear equations describes the relationship between the number of regular tickets, $r$, and VIP tickets, $v$ sold:

$$3r + 5v = 60$$

$$2r + 4v = 40$$

To find the number of regular tickets sold, solve this system of equations. Enter your answer as a fraction if necessary.