Answer
$3 \times 10^8$ blinks in a lifetime.
Work Step by Step
Assume 1 blink every 5 seconds during waking hours, and that the person is awake for 16 hours per day, or 57600 s.
$\frac{1 blink}{5s}\frac{57600s}{day}\frac{365days}{year}\frac{80years}{life}=3\times10^8\frac{blinks}{lifetime}$
