Solve the Problem $V$ , in Dollars, of a Shopkeeper's Inventory Software Program Is

Multiple Choice

Solve the problem.
-The value $V$ , in dollars, of a shopkeeper's inventory software program is given by $V=-20 t+200$ , where $t$ is the number of years since the shopkeeper first bought the program. After how many years is the value of the software $\$ 120$ ?

A) 3 yr
B) $4 \mathrm{yr}$
C) $5 \mathrm{yr}$
D) $6 \mathrm{yr}$