Question 1191072
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Olivia can ride her bike 4 miles per hour faster than Ted can ride his bike. 
If Olivia can go 30 miles in the same time that Ted can go 15 miles, what are their speeds?
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<pre>
Let x = Ted' speed, in miles per hour.

Then the Alivia' speed is (x+4) mph.


Write the time equation

    {{{30/(x+4)}}} = {{{15/x}}}    hours.


Solve it. Start cross-multiplying; then simplify

    30x = 15*(x+4)

    30x = 15x + 60

    30x - 15x = 60

       15x    = 60

         x    = 60/15 = 4.


<U>ANSWER</U>.  Ted' speed is 4 mph.  Olivia' speed is 4+4 = 8 mph.
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Solved.