Question 516258
Twenty pounds of trail mix are made by mixing 10 pounds of raisins worth $3 per pound with peanuts worth $4 per pound and M&M's worth $5 per pound. How many pounds of peanuts must be used if the mixture is to be worth $3.79 per pound?

raisins-----------10---------------3
peanuts-----------x---------------4
M&M--------------(20-(10+x))-------5 
Mixture-----------20-------------3.79

10*3+4*x+5(10-x)=20*3.79

30+4x+50-5x=75.8

-x=75.8-80
x= 4.2 pounds  peanuts
M&M=>(10-4.2)=5.8 pounds

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