Question 1089353
<pre>
             SPEED       TIME      DISTANCE
DOWNHL        r          1.5        d
UPHILL       r-36        4.2        d
</pre>

{{{1.5r=4.2(r-36)}}}

-

{{{15r=42(r-36)}}}
{{{5r=14(r-36)}}}
{{{5r=14r-14*36}}}
{{{9r=14*36}}}
{{{highlight(r=56)}}}----downhill
{{{highlight(20)}}}-----uphill