Question 1208999
Many example exercises fit the form of this one.

Two cyclists leave a city at the same time, one going east and the other going west. The westbound cyclist 
bikes k mph faster than the eastbound cyclist. After t hours, they are d miles apart. How fast is each 
cyclist riding?


One unknown variable, x, the speed for the eastward cyclist
All other numbers are given.
<pre>
                 SPEED       TIME       DISTANCE
EASTWARD           x           t         xt         

WESTWARD           x+k         t        t(x+k)

TOTAL                                     d
</pre>
{{{highlight_green(xt+t(x+k)=d)}}}


{{{xt+tx+tk=d}}}

{{{tx+tx+tk=d}}}

{{{2tx=d-tk}}}

{{{highlight(x=(d-tk)/(2t))}}}