Sorry one more then im done,
A merchant has coffee worth $20 a pound that she wished to mix with 70 pounds of coffee workth $80 a pound to get a mixture that can be sold for $40 a pound. How many pounds of the $20 coffee should be used??

Question

Sorry one more then im done, 
A merchant has coffee worth $20 a pound that she wished to mix with 70 pounds of coffee workth $80 a pound to get a mixture that can be sold for $40 a pound. How many pounds of the $20 coffee should be used??

anonymous · Answer

20x+80(70)=40(x+70)

20x+5600=40x+2800

40x-20x=5600-2800

20x=2800

x=140 pounds