Question 996373
Common form of travel rates exercise.


<a href="http://www.algebra.com/my/Uniform-Rates-Travel%3A-same-direction-but-different-travel-times-meet-when%3F.lesson?content_action=show_dev">Most directly related.  http://www.algebra.com/my/Uniform-Rates-Travel%3A-same-direction-but-different-travel-times-meet-when%3F.lesson?content_action=show_dev</a>


<a href="http://www.algebra.com/my/Uniform-Rates-Travel%3A-Two-Speeds-Differ-by-Constant-Same-Distance.lesson?content_action=show_dev">http://www.algebra.com/my/Uniform-Rates-Travel%3A-Two-Speeds-Differ-by-Constant-Same-Distance.lesson?content_action=show_dev</a>


Analyzing your example, Jessica traveled 3 hours, and if she left 1 hour AFTER Bill, then Bill traveled  3+1 hours.  We can make this data table:
<pre>
         speed    time     distance
BILL       r       3+1      d
JESSICA    80      3        d
</pre>

{{{system(r*4=d,80*3=d)}}}


Simple substitution for d.
{{{r=d/4}}}
{{{r=(80*3)/4}}}
{{{highlight(r=60)}}}