<![CDATA[<span class="pln">
</span><span class="typ">The</span><span class="pln"> distance </span><span class="kwd">from</span><span class="pln"> A to B </span><span class="kwd">is</span><span class="pln"> given </span><span class="kwd">as</span><span class="pln"> d km</span><span class="pun">.</span><span class="pln">
</span><span class="typ">The</span><span class="pln"> average speed </span><span class="kwd">is</span><span class="pln"> calculated </span><span class="kwd">using</span><span class="pln"> the formula average speed </span><span class="pun">=</span><span class="pln"> total distance traveled </span><span class="pun">/</span><span class="pln"> total time taken</span><span class="pun">.</span><span class="pln">
</span><span class="typ">The</span><span class="pln"> total distance traveled </span><span class="kwd">is</span><span class="pln"> given </span><span class="kwd">as</span><span class="pln"> </span><span class="lit">2d</span><span class="pln"> km</span><span class="pun">,</span><span class="pln"> which </span><span class="kwd">is</span><span class="pln"> the distance </span><span class="kwd">from</span><span class="pln"> A to B plus the distance </span><span class="kwd">from</span><span class="pln"> B to A</span><span class="pun">.</span><span class="pln">
</span><span class="typ">The</span><span class="pln"> total time taken </span><span class="kwd">is</span><span class="pln"> calculated </span><span class="kwd">by</span><span class="pln"> adding the time taken to travel </span><span class="kwd">from</span><span class="pln"> A to B to the time taken to travel </span><span class="kwd">from</span><span class="pln"> B to A</span><span class="pun">.</span><span class="pln">
</span><span class="typ">The</span><span class="pln"> time taken to travel </span><span class="kwd">from</span><span class="pln"> A to B </span><span class="kwd">is</span><span class="pln"> given </span><span class="kwd">as</span><span class="pln"> d</span><span class="pun">/</span><span class="lit">20</span><span class="pln"> hours</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">and</span><span class="pln"> the time taken to travel </span><span class="kwd">from</span><span class="pln"> B to A </span><span class="kwd">is</span><span class="pln"> given </span><span class="kwd">as</span><span class="pln"> d</span><span class="pun">/</span><span class="lit">30</span><span class="pln"> hours</span><span class="pun">.</span><span class="pln">
</span><span class="typ">Plugging</span><span class="pln"> the values </span><span class="kwd">for</span><span class="pln"> total distance traveled </span><span class="kwd">and</span><span class="pln"> total time taken </span><span class="kwd">into</span><span class="pln"> the formula </span><span class="kwd">for</span><span class="pln"> average speed</span><span class="pun">,</span><span class="pln">
we </span><span class="kwd">get</span><span class="pln"> average speed </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="lit">2d</span><span class="pln"> km</span><span class="pun">)</span><span class="pln"> </span><span class="pun">/</span><span class="pln"> </span><span class="pun">[(</span><span class="pln">d</span><span class="pun">/</span><span class="lit">20</span><span class="pln"> hours</span><span class="pun">)</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> </span><span class="pun">(</span><span class="pln">d</span><span class="pun">/</span><span class="lit">30</span><span class="pln"> hours</span><span class="pun">)].</span><span class="pln">
</span><span class="typ">Simplifying</span><span class="pln"> the expression </span><span class="kwd">for</span><span class="pln"> total time taken</span><span class="pun">,</span><span class="pln"> we </span><span class="kwd">get</span><span class="pln"> average speed </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="lit">2d</span><span class="pln"> km</span><span class="pun">)</span><span class="pln"> </span><span class="pun">/</span><span class="pln"> </span><span class="pun">[</span><span class="lit">5d</span><span class="pun">/</span><span class="lit">60</span><span class="pln"> hours</span><span class="pun">].</span><span class="pln">
</span><span class="typ">Finally</span><span class="pun">,</span><span class="pln"> we can solve </span><span class="kwd">for</span><span class="pln"> the average speed </span><span class="kwd">by</span><span class="pln"> dividing both sides </span><span class="kwd">of</span><span class="pln"> the equation </span><span class="kwd">by</span><span class="pln"> </span><span class="lit">5d</span><span class="pun">/</span><span class="lit">60</span><span class="pln"> hours</span><span class="pun">,</span><span class="pln">
which gives us average speed </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="lit">2d</span><span class="pln"> km</span><span class="pun">)</span><span class="pln"> </span><span class="pun">/</span><span class="pln"> </span><span class="pun">(</span><span class="lit">5d</span><span class="pun">/</span><span class="lit">60</span><span class="pln"> hours</span><span class="pun">)</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="lit">24</span><span class="pln"> km</span><span class="pun">/</span><span class="pln">hr
</span>]]>
Time and Distance