EXPLANATION
Let's see the facts:
Bag weight = 100 pound
Cost = 3.5/pound
Mix-->
Costa Rica Columbian
4/pound 3/pound
Let's call x to the amount of coffee from Costa Rica and y to the amount of coffee from Columbian, the equation would be:
Bag= x + y = 100
Isolating y:
y= 100 - x
We also want to sell it for $3.5
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Substituting terms:
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Multiplying both sides by 100:
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Applying the distributive property:
4x + 3y = 350
Substituting y=100 - x on it:
4x + 3(100-x) = 350
Applying the distributive property:
4x + 300 -3x = 350
Grouping and adding like terms:
x + 300 = 350
Subtracting -300 to both sides:
x = 350 - 300
Subtracting numbers:
x = 50
Now, we need to find the y-value applying the first equation:
y= 100 - 50 = 50
Answers: The amount of Costa Rica coffee is 50 pounds and the amount of Columbian coffee is 50 pounds.