Question 1151690
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(a)  

    (1)   {{{16200/x}}}.

    (2)   {{{16200/(x+3)}}}


(b)       {{{16200/x}}} - {{{16200/(x+3)}}} = 60.


          To solve it, first cancel the factor 60 in both side


              {{{270/x}}} - {{{270/(x+3)}}} = 1


          Multiply both sides by x*(x+3)


               270*(x+3) - 270x = x*(x+3)

               x^2 + 3x - 810 = 0

               (x+30)*(x-27) = 0.


         Of the two roots  x= -30  and  x= 27, only positive x= 27 is the solution.



(c)      Thus the number of calculators before discount was 27, 

             and the price for each single calculator was  {{{16200/27}}} = 600.


         After discount, the number of calculators  was  27+3 = 30, 

             and the price for each single calculator was {{{16200/30}}} = 540.


         The discount from the price for each single calculator is  {{{(600-540)/600}}} = {{{60/600}}} = 0.1 = 10%.
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