Question 739016:  Ashley's Coffee Shop makes a blend that is a mixture of two types of coffee. Type A coffee costs Ashley  per pound, and type B coffee costs  per pound. This month's blend used three times as many pounds of type B coffee as type A, for a total cost of  . How many pounds of type A coffee were used? 
 Answer by josgarithmetic(39630)      (Show Source): 
You can  put this solution on YOUR website! Put in some numbers, even if they are variables.
 
 
Type A coffee costs Ashley  A dollars per pound, and type B coffee costs  B dollars per pound. This month's blend used three times as many pounds of type B coffee as type A, for a total cost of  C dollars. How many pounds, a, of type A coffee were used?
 
 
That is using a = pounds of type A coffee  
and 
b = pounds of type B coffee
 
 
The ratio statement gives us  , where b is the amount of type B coffee in this month's blend.
 
 
Accounting for cost,  .
 
 
The description does not clearly tell which variables are known or unknown; but only describes their occurrence or existence.  The QUESTION asks for how many pounds of type A coffee, the number which is here assigned as "a".  
 
 
You have two equation, and either one or two unknown, a and b.  We want to solve just for a: 
b/a=3 gives us  .  SUBSTITUTE into the cost equation. 
  
And continue solution steps to get a, 
  
  
  
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