Question 1089570
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Two cars start moving simultaneously in the same direction. The first car moves at 64 mph; the speed of the second car is 40 mph. 
A half-hour later, another car starts moving in the same direction. The third car reaches the first one 1.5 hours after it reached the second car.
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<pre>
Let x be the speed of the third car in mph, which is under the question.

The third car reaches the second one in {{{20/(x-40)}}} hours.

The third car reaches the first one in {{{32/(x-64)}}} hours.

The condition says that 

{{{32/(x-64)}}} - {{{20/(x-40)}}} = 1.5   hour.


Simplify and solve for x.


You first step is to multiply both sides of the equation by (x-64)*(x-40).


I solved it mentally and got the answer x= 80 mph.
</pre>


For many other solved catching up problems/samples see the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Typical-catching-up-Travel-and-Distance-problems.lesson>Travel and Distance problems for two bodies moving in the same direction (catching up)</A>

in this site.



Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lesson is the part of this textbook under the section "<U>Word problems</U>", &nbsp;the topic "<U>Travel and Distance problems</U>".