Last Week a Theater Purchased an Air Conditioner For $\$ 24,000$

Last week a theater purchased an air conditioner for $\$ 24,000$ . The air conditioner's value will depreciate $\$ 4,000$ a year for each of the next 6 years. The equation $y=24,000-4,000 x, 0 \leq x \leq 6$ models the air conditioner's value, where $y$ is the value of the air conditioner and $x$ is the number of years after purchase. In how many years will the value of the air conditioner be $\$ 8,000$ ?