mya hs coffee worth $40. a pound that she wishes to mix 40 pounds of coffee that worth $90. a pound,so she can get a mixture that can be sold for 80. a pound.How many pounds of the $40. a pound coffee should she use?
Let the amount of $40 coffee used be x pounds.
The cost of this x pounds of coffee is $40x.
Since she is mixing 40 pounds of coffee worth $90 a pound, the cost of these 40 pounds of coffee will be 40 * 90 = $3600
Thus, the total cost of these two types of coffee used will be: $(40x + 3600).
The total weight of this coffee will be: (x + 40) pounds.
This means that the cost of a pound of this mixture is: $(40x + 3600) / (x + 40).
Since each pound of the mixture is to be sold at $80 a pound, we have:
(40x + 3600) / (x + 40) = 80
40x + 3600 = 80(x + 40)
40x + 3600 = 80x + 3200
80x - 40x = 3600 - 3200
40x = 400
x = 400 / 40
x = 10
Hence, she should use 10 pounds of the $40 coffee.