Let Brian's steps have a measure of 1, and Richard's steps have a measure of k. Then after each walks 5 steps away from the other, their distance apart is
... 5 + 5k
We are told that distance is equal to 9 of Richard's steps, so is equal to 9k.
... 5 + 5k = 9k
... 5 = 4k . . . . . . . subtract 5k
... 5/4 = k . . . . . . divide by 4
Richard's steps are 5/4 the size of Brian's steps. The appropriate selection is
... b) 5/4
