Question 279596
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Pablo can drive 5 times as fast as Oscar can ride his bicycle. If it takes Oscar 4 hours longer than Pablo 
to travel 90 miles, how fast can Oscar ride his bicycle?
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        The solution and the answer in the post by @mananth both are incorrect due to arithmetic errors.

        I came to provide a correct solution.



<pre>
Let Oscar' speed be x miles per hour

Pablo's speed = 5x miles per hour

t= distance /rate

{{{90/x}}} = Oscar's time

Pablo's time = {{{90/5x}}}


Time equation

    {{{90/x}}} + 4 = {{{90/5x}}}


Simplify and find x

    {{{90/x}}} - {{{90/5x}}} = 4

    {{{(90/x)*(1-1/5)}}} = 4

    {{{(90/x)*(4/5)}}} = 4

    {{{90/x}}} = 5

    x = {{{90/5}}} = 18.


<U>ANSWER</U>.  Oscar' speed riding bicycle is 18 miles per hour.
</pre>

Solved correctly.