Question

a store mixes kenyan coffee worth $11 per kilogram and turkish coffee worth $13 per kilo gram. The mixture is to sell for $12 per kilogram. Find how much of each should be used to make a 588 kilo mixture.

Answer 1

amount of Kenyan coffee --- x
amount of Turkish coffee --- 588

11x + 13(588-x) = 12(588)

solve for x and you got it

Answer 2

I have x=58.8

Answer 3

Without even checking the answer by substitution, it sound unreasonable right from the start.
Since the 588 kg sells for $12 and was mixed from a $11 and a $13 source, we would expect the split to be about half way.

11x + 7644 - 13x = 7056
-2x = -588
x = 294

well, what a surprise.