Answer:
The total time is [tex]\bf{52850~Yr}[/tex].
Explanation:
Given:
The distance between Galactic Capitol and Earth is, [tex]d = 2.5 \times 10^{20}~m[/tex]
The speed of light is, [tex]c = 3 \times 10^{8}~m/s[/tex]
The time taken by the message to reach and come back to Earth is given by
[tex]t &=& \dfrac{2d}{c}\\~~&=& \dfrac{2(2.5 \times 10^{20}~m)}{3 \times 10^{8}~m/s}\\~~&=& 1.6 \times 10^{12}~s\\~~&=& \dfrac{1.6 \times 10^{12}~s}{(86400 \times 365)~s}~Yr\\~~&\approx& 52849~Yr[/tex]
In addition they take 1 year to decide to reply.
Thus, the total time is [tex]25850~Yr[/tex].
