The Cashews

    9)  Mr. Riley runs a corner grocery store.  He sells whole 
cashews for $4 a pound and cashew bits and pieces for $3 a pound.
To offer his customers more of a selection, he was planning on mixing
up a 100-pound combination of both kinds of cashews to sell for
$3.35 a pound.  In order for his profit to remain the same, how
many pounds of the $4 cashews, and how many pounds of the $3 bits
and pieces would he need to combine for this?    

        4.00(x) + 3.00(100-x) = 3.35(100)

        "x" = the number of pounds.

    Eliminate the decimals by multiplying by 100:

        400(x) + 300(100-x) = 335(100)

        400x + 30,000 -300x = 33,500

        100x + 30,000 = 33,500

        100x =  3,500

        x  =  35

    Since "x" equals 35, then that means that 35 pounds of the $4
cachews will be mixed in with 65  (100-35) pounds of the $3 cashew
bits & pieces.

    Here's what else we can now figure out to double check 
our work:

    35 pounds of the $4 cashews............$140.00
    65 pounds of the $3 bits & pieces......$195.00
    -------------------------------------------------
   100 pounds total                        $335.00

     Selling 100 pounds at $3.35 a pound = $335.00