Answer:
[tex]\large \boxed{\sf \bold{D.} \ 9 \ years}[/tex]
Step-by-step explanation:
[tex]S(t) = -105t + 945[/tex]
For the value to depreciate completely, the amount has to be equal to 0 dollars.
Set S(t) to 0.
[tex]0 = -105t + 945[/tex]
Solve for the time t.
Subtract 945 from both sides.
[tex]0 -945= -105t + 945-945[/tex]
[tex]-945=-105t[/tex]
Divide both sides by -105.
[tex]\displaystyle \frac{-945}{-105}=\frac{-105t}{-105}[/tex]
[tex]9=t[/tex]
It will take 9 years for the saw to depreciate completely.
