In racing over a given distance at uniform speed Bryan can b

In racing over a given distance at uniform speed Bryan can beat Sean by 20
meters, Sean can beat Stephen by 10 meters, and Bryan can beat Stephen by 28
meters. How many meters is the distance over which they are racing?

d=distance
rt=d
b=sean+20
sean=st+10
sean-st=10
b=st+28
sean+20=st+28
sean-st=8
sean-st=10
Something is wrong.
8 cannot equal 10