A person wishes to mix coffee worth $9 per lb with coffee worth $3 per lb to get 240 lb of a mixture worth $5 per lb. how many pounds of the $9 and the $3 coffees will be needed?
Let x= lbs of the 9$ mix y= lbs of the 3$ mix x+y=240 9x+3y=1200
Divide the second equation by -3 then combine to get -2x = -160. Divide -160 by -2 to get the number of lbs of the $9 mix, 80lbs. Subtract 80lbs from the lbs of the 5$ mix, 240lbs, to get the number of lbs of the $3 mix, 160lbs.
