SAT Math Practice Question

A company purchased a machine valued at $\$ 120,000$. The value of the machine depreciates by the same amount each year so that after 10 years the value will be $\$ 30,000$. Which of the following equations gives the value, $v$, of the machine, in dollars, $t$ years after it was purchased for $0 \leq t \leq 10 ?$

1. A.$v=30,000-9,000 t$
2. B.$v=120,000-9,000 t$
3. C.$v=120,000+9,000 t$
4. D.$v=120,000-30,000 t$