In a town, the cost of a movie ticket is represented by the equation:

$$ y = 12x + 5 $$

where $y$ is the total cost in dollars and $x$ is the number of tickets purchased.

At a local event, the cost of attending the movie changes according to the following linear equation:

$$ y = 15x - 10 $$

where $y$ is again the total cost in dollars. Determine how many tickets must be sold at both events for the total costs to be equal. What is that number of tickets?