SOLUTION: A collection of 30 coins worth $5.50 consists of nickels, dimes, and quarters. There are twice as many dimes as nickels. How many quarters are there? please and thank you!!

Algebra ->  Customizable Word Problem Solvers  -> Coins -> SOLUTION: A collection of 30 coins worth $5.50 consists of nickels, dimes, and quarters. There are twice as many dimes as nickels. How many quarters are there? please and thank you!!      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 314797: A collection of 30 coins worth $5.50 consists of nickels, dimes, and quarters. There are twice as many dimes as nickels. How many quarters are there?
please and thank you!!
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
N-number of nickels
D-number of dimes
Q-number of quarters
.
.
1.N%2BD%2BQ=30
2.5N%2B10D%2B25Q=550
3.D=2N
Substitute eq. 3 into both 1 and 2.
N%2B2N%2BQ=30
4.3N%2BQ=30
.
.
5N%2B10%282N%29%2B25Q=550
5N%2B20N%2B25Q=550
25N%2B25Q=550
5.N%2BQ=22
Multiply eq. 4 by (-1) and add to eq. 5.
-3N-Q%2BN%2BQ=-30%2B22
-2N=-8
highlight%28N=4%29
Then from eq. 5,
4%2BQ=22
highlight%28Q=18%29
and from eq. 3,
D=2N
highlight%28+D=8%29