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A coffee merchant wants to make 6 pounds of a blend of coffee costing five dollars per pound. The blend is made using a six dollar per pound grade coffee and a three dollar per pound grade of coffee. How many pounds of each of these grades should be used?

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Limosa

Answer:

We should use 4 pounds of $6 coffee and 2 pounds of $3 coffee for the blend.

Step-by-step explanation:

The blend should,

Cost = $5

Weigh = 6 pounds.

Lets take the weight of $6 coffee as [tex]x[/tex] pounds

And lets take the weight of $3 coffee as [tex]y[/tex] pounds.

Lets write an equation for the weight of the blend,

[tex]x+y=6[/tex] <---------- 1st equation.

[tex]\frac{6x+3y}{x+y} =5[/tex]

=[tex]6x+3y=5x+5y[/tex]

=[tex]x=2y[/tex] <---------- 2nd equation

We can substitute to x in 1st equation from 2nd equation,

⇒[tex]2y+y=6[/tex]

=[tex]2y+y=6[/tex]

=[tex]3y=6[/tex]

=[tex]y=2[/tex]

We can substitute y value to 2nd equation to find x,

⇒[tex]x=2y[/tex]

=[tex]x=2*2[/tex]=[tex]x=4[/tex]

Therefore, we should use 4 pounds of $6 coffee and 2 pounds of $3 coffee for the blend.