Question 1070839
<pre>
              SPEED       TIME      DISTANCE
A to B         r          3.5       d=(r)(3.5)
B to A        r+20        3         d=(3)(r+20)
Totals                   6.5       3.5r+3r+60
</pre>


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{{{3.5r=3r+60}}}
{{{0.5r=60}}}
{{{highlight_green(r=120(kilometers/hour))}}}
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WHOLE JOURNEY, average speed:
{{{(6.5*120+60)/6.5}}}


{{{highlight(129(kilometers/hour))}}}