Let r$($f$)=(12,1-1,4$t$).$ Calculate the derivative of r$($f$)-$ a$($t$)$ at t $=3$ assuming that

a$(3)=(9,-7,8)$

a$\text{'}(3)=(9,2,2)$

$($Use decimal notation. Give your answer as a whole or exact number.$)$

$=$

$=3$

Enter numeric value