Problema Solution
A merchant has coffee worth $60 a pound that she wishes to mix with 70 pounds of coffee worth $90 a pound to get a mixture that is worth $70 a pound. How many pounds of the $60 coffee should be used?
Answer provided by our tutors
We don't know how much $60 coffee should be used. Call it x.
We do know how much of the $90 coffee is used. 70 lbs.
When mixed, there is x + 70 pounds of coffee, and that is worth $70/lb.
We can set up an equation: 60x + 6300 = (x+70)*70.
Solving for x reveals the answer.
60x +6300 = 70x +4900 --> 1400 = 10x ---> 140=x