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A postal clerk sold some 15 cent stamps and some 25 cent stamps. Altogether, 15 stamps were sold for a total cost of $\$3.15$. How many of each type of stamp were sold?

 Feb 10, 2021
 #1
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Let the  number   of  15 cent stamps   = x

Let the number  of  25 cent stamps = 15   -  x

 

So

 

15x  +  25 ( 15  - x)   =  315

 

15x  +  375   - 25x =   315

 

15x  - 25x  =   315  - 375

 

-10x  =  - 60      divide  both sides by -10

 

x =  6   =   the number of 15 cent stamps sold

 

15  -  x  =   15  -  6  =   9    = the number  of 25 cent stamps sold

 

 

 

cool cool cool

 Feb 10, 2021

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