SOLUTION: help a coffee shop manager to find the amount of a certain type of coffee that sells for $5 per kilogram which should be mixed with the 30kgs of another type of coffee which sells

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Question 1199152: help a coffee shop manager to find the amount of a certain type of coffee that sells for $5 per kilogram which should be mixed with the 30kgs of another type of coffee which sells for $9 per kg in order to make a new flavor of coffee which she sells for $7 per kilogram
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
$5 per kg
30 kg of $9 per kg
resulting mixture $7 per kg

u kilograms of the $5 per kg coffee to use

5u%2B9%2A30=7%28u%2B30%29------to account for cost;
Solve for u.

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


The setup for a formal algebraic solution....

(The cost of 30kg of coffee worth $9 per kg), plus (the cost of x kg of coffee worth $5 per kg), equals the cost of ((30+x) kg of coffee worth $7 per kg):

30%289%29+%2B+x%285%29+=+%2830%2Bx%29%287%29

Solve using basic algebra....

A quick, informal, common sense solution....

The price per kg of the mixture is exactly halfway between the prices for the two kinds of coffee; that means the numbers of kg of the two kinds of coffee are the same.

ANSWER: 30kg