Question 284297
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Fred and Desi left Steamtown Mall at 9:00 am and began walking in opposite directions. 
At 1:00 pm that same day they were 20 miles apart. If Fred walks 0.5 mph slower than Desi, 
what is Desi' speed of walking?
A. 2.25 mph B. 2.75 mph C. 3.5 mph D. 5 mph E. None of these.
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        In the post by @mananth, the treatment is not adequate to the problem.
        Due to this reason, the solution and the answer are incorrect.


        I came to bring a correct solution.



let desi's speed be x mph
Fred's speed = x-0.5 mph
In 4 hours Desi has walked 4x miles
In 4 hours Fred has walked 4(x-0.5) miles = 4x-2
4x + (4x -2) = 20
8x = 22
x = {{{22/8}}} = {{{11/4}}} = 2.75 mph &nbsp;&nbsp;&nbsp;&nbsp;Desi' speed&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<<<---===  <U>ANSWER</U>


<U>CHECK</U>.  &nbsp;&nbsp;The distance apart in 4 hours, &nbsp;at 1:00 pm, &nbsp;is 4*2.75 + 4*(2.75 - 0.5) = 20 miles.  &nbsp;&nbsp;&nbsp;&nbsp;! Precisely correct !


Solved correctly.