in order for coffee to be labeled "kona blend" it must contain at least 65% kona beans barking dog roasters has 50 pounds of 100% kona coffee beans how much Sumatran coffee must thay add to the kona beans if they wish to market the Kona coffee as kona blend?

Solution:

X Sumatran coffee must be added

(50+x)*65% = 50

x= 26.92

So at most  26.92 pounds of Sumatran coffee must be added