SOLUTION: sandy has a total of 35 coins in her money jar. If Sandy's jar contains only nickels and dimes and the value of all the coins is 2.50 how many nickels does Sandy have?

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Question 966319: sandy has a total of 35 coins in her money jar. If Sandy's jar contains only nickels and dimes and the value of all the coins is 2.50 how many nickels does Sandy have?
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
Let the number of nickels be x
Then the number of dimes, using
ONE PART = TOTAL MINUS OTHER PART,
is 35-x.
                      Value      Value
Type       Number       of         of
 of          of        EACH       ALL
coin        coins      coin      coins
-------------------------------------------
nickels     x        $0.05     $0.05x
dimes    35-x        $0.10     $0.10(35-x)
-------------------------------------------
TOTALS      35        -----    $2.50

 The equation comes from the column on the right

  %28matrix%284%2C1%2CValue%2Cof%2CALL%2Cnickels%29%29%22%22%2B%22%22%28matrix%284%2C1%2CValue%2Cof%2CALL%2Cdimes%29%29%22%22=%22%22%28matrix%285%2C1%2CTotal%2Cvalue%2Cof%2CALL%2Ccoins%29%29

       0.05x + 0.10(35-x) = 2.50

Get rid of decimals by multiplying every term by 100:

            5x + 10(35-x) = 250

           5x + 350 - 10x = 250

                -5x + 350 = 250

                      -5x = -100

                        x = 20 = the number of nickels.

The number of dimes is 35-x or 35-20 or 15 dimes.

Checking:  20 nickels is $1.00 and 15 dimes is $1.50

            And indeed $1.00 + $1.50 = $2.50
Edwin