Answer: c 12 pounds of the $5.50-per-pound coffee, 8 pounds of the $9.20-per-pound coffee
Step-by-step explanation:
Let x = Number of pound of first king.
y= Number of pound of second kind.
As per given , we have
[tex]x+y=20\Rightarrow\ y= 20-x (i)\\\\\\9.20x +5.50 y= 6.98(20) \\\Rightarrow\ 9.20x +5.50 y=139.6 (ii)[/tex]
substitute value of y from (i) in (ii), we get
[tex]9.20x +5.50(20-x) =139.6\\\\\Rightarrow\ 9.20x +5.50(20)-5.50x =139.6\\\\\Rightarrow\ 9.20x-5.50x +110 =139.6\\\\\Rightarrow\ 3.7x =139.6-110\\\\\Rightarrow\ 3.7x =29.6\\\\\Rightarrow\ x=\dfrac{29.6}{3.7}=\dfrac{296}{37}\\\\\Rightarrow\ x=8[/tex]
Put this in (i), we get y= 20-8 = 12
Hence, he should blend 12 pounds of the $5.50-per-pound coffee, 8 pounds of the $9.20-per-pound coffee.
So the correct option is c.