Critical Thinking

Assume two galaxies are $2.00 \times 10^{2} \textrm{ }\text{Mly}$ apart. (a) How fast are they separating due to space expansion? (b) Now suppose a third galaxy is located $2.00 \times 10^{2} \textrm{ }\text{Mly}$ along a line that is a perpendicular bisector of the line segment between the first two galaxies. How fast is this galaxy separating from either of the other two galaxies? (c) Why would the third galaxy appear to be receding from both of the initially mentioned galaxies at the same rate? (d) How would the apparent motion be detected?