Question 23737
Let x = number of pennies, (since this is at the end of the first phrase).
2x = number of nickels


Now, getting the number of dimes is a little tricky.  You have accounted for a total of x + 2x = 3x in pennies and nickels, and there are a total of 45 coins in all.  The number of dimes is 45 minus all the rest of the coins.  That is,


45 - 3x = number of dimes


Values of the coins in CENTS will be the value of each coin times the number of coins:
1*x = value of pennies
5*(2x) = value of nickels 
10*(45-3x) = value of dimes


The equation is based upon the total value of the coins.  Be sure that if you are doing the problem in cents, then everything is in cents:


1x + 5(2x) + 10(45-3x) = 260 cents
1x + 10x + 450 - 30x = 260
-19x + 450 = 260


Subtract 450 from each side:
-19x + 450 -450 = 260-450
-19x = -190


Divide both sides by -19 and HOPE it comes out even!!  Remember, it CAN'T come out to a fraction, and it CAN'T come out to a negative number!

{{{-19x = -190}}}
{{{(-19x)/-19 = (-190)/-19}}}

x = 10 Pennies
2x = 20 Nickels
45-3x = 45 - 30 = 15 Dimes


Check the values:  
P = $0.10
N = $1.00
D = $1.50

Total= $2.60
It checks!


R^2 at SCC