Answer
(a) away from
(b) $0.12c$
Work Step by Step
(a) We know that the galaxy is moving away from the Earth. According to the Doppler Effect, the frequency of the electromagnetic radiation measured by an observer is less than what it was when emitted if the source is receding.
(b) As $f^{\prime}=f-\frac{12f}{100}$
$\implies f^{\prime}=0.88f$
Now $0.88f=f(1-\frac{u}{c})$
This simplifies to:
$\frac{u}{c}=1-0.88$
$\frac{u}{c}=0.12$
$\implies u=0.12c$
