<PRE><B>Question 840153</B>
r= unknown speed
r is in meters per seconds
time is in seconds


________________speed___________time____________distance
North___________r_______________(___)___________1200
South___________r_______________(___)___________1800
Total__________________________200


{{{R*T=D}}} which means {{{T=D/R}}}.  Fill in the time expressions:


________________speed___________time____________distance
North___________r_______________1200/r___________1200
South___________r_______________1800/r___________1800
Total__________________________200


Most important first equation to solve is {{{1200/r+1800/r=200}}}.
Simplify and solve for r.
{{{(12+18)/r=2}}}
{{{30/r=2}}}
{{{30/2=r}}}
{{{highlight(r=15)}}} meters per second


-
(A) total distance traveled 1200+1800=3000 meters.
(B) actual displacement, because he backtracked is 1800-1200=600 meters.


The speed was just solved, either direction, as {{{r=15}}}.
(D) VELOCITY?  This is speed AND direction.
600 meters SOUTH in 200 seconds, SOUTH {{{600/200=highlight(3/2=1.5)}}}  meters per second.</PRE>