February 23, 2017

Homework Help: Algebra

Posted by Valeria on Friday, February 20, 2009 at 4:26pm.

The Coffee Counter charges $9.00 per pound for Kenyan French Roast coffee and $8.00 per pound for Sumatran coffee. How much of each type should be used to make a 20-lb blend that sells for $8.40 per pound?

Here are the 2 equations (or system of equations) I created:

K = lbs of Kenyan French Roast coffee
S = lbs of Sumatran coffee

k + s = 20
9k + 8s = 8.40

I then multiplied the top equation by -8 so I could do the elimination method to solve.

That got made k+s=20 into -8k + -8s = -160.

Of course, when I added those two equations together, I got k = -151.6, which couldn't possibly be right.

Are my two equations right, and can you see where I went wrong?

¢¾ Valeria ¢¾

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