In order to find this, we can first just see where the graphs intersect each other. This will give us the solution set.
As for what it represents, the x value in the increase in temperature and the y value is the increase in customers.
Therefore, we know that we want the temperature to go up by 1 (although we don't know the units) and that would result in the amount of people coming, and staying longer by 4 (again, we don't know the units of measure).