Question 999540
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Let us assume for a minute that all the stamps cost  45 cents each. 

Then the total cost would be  50*45 = 2250 cents = $22.50,  which is in  $2 less than  $24.50.

It is clear that the difference is due to presence of  $0.65  stamps that we intently counted as  0.45. 

It is also clear that the number of these  $0.65  stamps is  {{{2/(0.65-0.45)}}} = {{{2/0.20}}} = 10 to compensate the difference.


It gives the answer:  10 stamps in  65 cents  and  50-10 = 40  stamps in  45 cents.


For more problems that can be solved using this approach see the lessons 

&nbsp;&nbsp;&nbsp;&nbsp;<A HREF=http://www.algebra.com/algebra/homework/word/misc/Problem-on-animals-at-a-farm.lesson>Problem on animals at a farm</A>  

&nbsp;&nbsp;&nbsp;&nbsp;<A HREF=http://www.algebra.com/algebra/homework/word/misc/Problem-on-tablets-in-containers.lesson>Problem on pills in containers</A> &nbsp;&nbsp;&nbsp;&nbsp;and

&nbsp;&nbsp;&nbsp;&nbsp;<A HREF=http://www.algebra.com/algebra/homework/word/misc/What-type-of-problems-are-these.lesson>What type of problems are these?</A> 

under the topic &nbsp;<B>Miscellaneous Word Problems</B>&nbsp; of the section &nbsp;<B>Word problems</B>&nbsp; in this site.