Question 1209393
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<pre>

Work with common denominator 12*7


    {{{1/(1*4)}}} + {{{1/(4*7)}}} + {{{1/(7*12)}}} = {{{(7*3)/(7*12)}}} + {{{3/(7*12)}}} + {{{1/(7*12)}}} = {{{(21 + 3 + 1)/(7*12)}}} = {{{25/84}}}.         <U>ANSWER</U>
</pre>

Solved.


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This is a typical and routine 5th grade assignment, where you 
don't have to think - you just have to follow the pre-set rules.