Question

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?

Thanks,
¢¾ Valeria ¢¾

Answer 1

your final cost for the 20 lb blend will be $168. K=$9 and S=$8. you have to find out how many pound of k plus how many pounds of s will equal 20 pounds and $168

Answer 2

You are making the same error as you did in your post at 5:26 pm

make your last equation 9k + 8s = 8.40(20)

(I got k=8, s = 12)