SOLUTION: Bill left school and drove toward the train station. One hour later Jessica left driving at 80 km/h in an effort to catch up to Bill. After driving for 3 hours Jessica finally caug

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Question 996373: Bill left school and drove toward the train station. One hour later Jessica left driving at 80 km/h in an effort to catch up to Bill. After driving for 3 hours Jessica finally caught up. Find bills average speed
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
Common form of travel rates exercise.

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

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

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:
         speed    time     distance
BILL       r       3+1      d
JESSICA    80      3        d

system%28r%2A4=d%2C80%2A3=d%29

Simple substitution for d.
r=d%2F4
r=%2880%2A3%29%2F4
highlight%28r=60%29