SOLUTION: A person exchanged 390 pennies for quarters, dimes and nickels. The number of dimes in the exchange was twice the number of quarters and the number of nickels was twice the number

Algebra ->  Customizable Word Problem Solvers  -> Coins -> SOLUTION: A person exchanged 390 pennies for quarters, dimes and nickels. The number of dimes in the exchange was twice the number of quarters and the number of nickels was twice the number       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 961320: A person exchanged 390 pennies for quarters, dimes and nickels. The number of dimes in the exchange was twice the number of quarters and the number of nickels was twice the number of dimes. How many of each coin type were in the exchange?
I set up the problem:
390 pennies=2D(.25) + 2N(.10) + Q(.25)
390 = .50D + .20N + .25Q
And now I'm stuck. Please help.
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39838) About Me  (Show Source):
You can put this solution on YOUR website!
system%2825q%2B10d%2B5n=390%2Cd=2q%2Cn=2d%29

system%285q%2B2d%2Bn=78%2Cd=2q%2Cn=2d%29

system%285q%2B2d%2Bn=78%2Cq=d%2F2%2Cn=2d%29

q and n are expressible in terms of d.

Answer by MathTherapy(10858) About Me  (Show Source):
You can put this solution on YOUR website!

A person exchanged 390 pennies for quarters, dimes and nickels. The number of dimes in the exchange was twice the number of quarters and the number of nickels was twice the number of dimes. How many of each coin type were in the exchange?
I set up the problem:
390 pennies=2D(.25) + 2N(.10) + Q(.25)
390 = .50D + .20N + .25Q
And now I'm stuck. Please help.
390 pennies = $3.90

JUST one (1) variable is NEEDED. I've chosen that variable to be Q



Let the number of quarters be Q

Then number of dimes was: 2Q

Also, number of nickels was: 2(2Q), or 4Q

We then get: .25Q + .1(2Q) + .05(4Q) = 3.9

.25Q + .2Q + .2Q = 3.9

.65Q = 3.9

Q, or number of quarters = 3.9%2F.65, or highlight_green%286%29

Number of dimes: 2(6), or highlight_green%2812%29

Number of nickels: 4(6), or highlight_green%2824%29