Nothing in my physics book addresses this question. Can someone please help??

Question

Two ice skaters, with masses of 69kg and 47kg , stand facing each other on a 19-m-wide frozen river. The skaters push off against each other, glide backward straight toward the river's edges, and reach the edges at exactly the same time.
How far did the 69kg skater glide?

Answer 1

69 v1 = 47 v2
so
v2 = (69/47)v1

19 = (v1+v2)t

19 (v1 + 1.47 v1) t
so
v1 t = distance of first = 19/2.47
= 7.69 meters