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

Solve the problem.
-The value $\mathrm { V }$ , in dollars, of a shopkeeper's inventory software program is given by $\mathrm { V } = - 40 \mathrm { t } + 250$ , where $t$ is the number of years since the shopkeeper first bought the program. After how many years is the value of the software $\$ 10$ ?

A) $6 \mathrm { yr }$
B) $8 \mathrm { yr }$
C) $7 \mathrm { yr }$
D) $5 \mathrm { yr }$