Answer:
83km
Step-by-step explanation:
Distance from the 256km marker to 138km marker.....is (256 - 138) = 118km
Then when he traces back to the 173km marker....he moves (173 - 138) = 35km but its in the opposite direction...so hence..its -35km(since when calculating displacement...direction has to be accounted for)...
Total displacement from the 256km marker
; 118 + (-35) = 83km