Question 1197658
<pre>
              SPEED      TIME          DISTANCE

GOING TO       r+24      315/(r+24)       315

RETURNING      r         315/r            315

TOTAL                     9       
</pre>
{{{315/r+315/(r+24)=9}}}---------simplify and solve.


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{{{35/r+35/(r+24)=1}}}


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{{{35(r+24)+35r=r^2+24r}}}
{{{70r+35*24=r^2+24r}}}
{{{r^2+24r-70r=35*24}}}
{{{r^2-46r=35*24}}}
{{{r^2-46r-840=0}}}

{{{r=(46+- sqrt(46^2+4*840))/2}}}

{{{r=(46+- sqrt(5476))/2}}}

{{{r=(46+74)/2}}}

{{{highlight(r=60)}}}


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Could also been done by factoring