Answer
The galaxy is receding at $2.38\times10^4 \ km/s$.
Work Step by Step
We use the equation for the velocity when the Doppler Effect is occurring to obtain: $ v = 3\times 10^8 \times (1- \frac{656}{708})=2.38\times10^4 \ km/s$
Given the frequencies, we see that the galaxy is receding at $2.38\times10^4 \ km/s$.
