Problema Solution
A merchant has coffee worth $20 a pound that she wishes to mix with 60 pounds of coffee worth $70 a pound to get a mixture that can be sold for $40 a pound. how many pounds of the $20 coffee should be used?
Answer provided by our tutors
Let the weight of $20 a pound coffee be x pounds.
We have 60 pounds of $70 a pound coffee.
Total weight of the $40 a pound mixture = (x + 60) pounds
Then, according to the question:
20x + 70*60 = 40*(x+60)
=> 20x + 4200 = 40x + 2400
=> 20x = 1800
=> x = 90
So, 90 pounds of $20 a pound coffee should be used.