Answer
See the explanation below.
Work Step by Step
Left-sided limit:$\qquad \displaystyle \lim_{t\rightarrow 20^{-}}v(t)=3(20)=60$
Right-sided limit:$\displaystyle \qquad \lim_{t\rightarrow 20^{+}}v(t)=174(20)-3420=60$
Interpretation:
Just before 1990 ($t=20$ means 20 years after 1970), the speed of the processors was nearing 60 MHz, and shortly after 1990, the speed of the processors was still close to 60 MHz.
