Question 1143494
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Newer machine produces  {{{7200/200}}} = 36 cans per minute.


The older machine produces  {{{7200/300}}} = 24 cans per minute.


Working together, the two machines produce  36 + 24 = 60 cans per minute.


Working together, the two machines will produce 7200 cans in  {{{7200/60}}} = 120 minutes = 2 hours.    <U>ANSWER</U>
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It is &nbsp;VERY &nbsp;SIMPLE &nbsp;and &nbsp;SIMPLEST &nbsp;joint work problem for 4-grade students, &nbsp;and there is no any need 
to use three-level fractions to solve it, &nbsp;as &nbsp;@josgarithmetic tries to teach you.


All you need to do is to divide integer numbers to find rate of work of each machine;
then add rates to find combined rate of work of two machines working together; 
and, &nbsp;finally, &nbsp;to divide the total production volume to this combined rate of work.


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If you want to see other similar solved problems and to wider your knowledge, look into the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Rate-of-work-word-problems/Special-joint-wok-problems-that-admit-and-require-an-alternative-solution-method.lesson>Special joint work problems that admit and require an alternative solution method</A>

in this site.