Question 966319
<pre>
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

  {{{(matrix(4,1,Value,of,ALL,nickels))}}}{{{""+""}}}{{{(matrix(4,1,Value,of,ALL,dimes))}}}{{{""=""}}}{{{(matrix(5,1,Total,value,of,ALL,coins))}}}

       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</pre>