SOLUTION: I need this by 6:00am! 20 coins, $2.30 you have to find how many coins is in the 20 coins. There are only quarters dimes and nickels. Nickels is twice of the quarters!

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Question 892277: I need this by 6:00am!
20 coins, $2.30 you have to find how many coins is in the 20 coins. There are only quarters dimes and nickels. Nickels is twice of the quarters!
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
(Earlier posted solution was wrong. Now CORRECTED here):

SOLUTION NOW CORRECT:

n,d,q for nickels, dimes, quarters.

Coin count: n%2Bd%2Bq=20

Money count: 0.05%2B0.1d%2B0.25q=2.30
5n%2B10d%2B25q=230
n%2B2d%2B5q=46

Given n,q relationship: n=2q

system%28n%2Bd%2Bq=20%2Cn%2B2d%2B5q=46%2Cn=2q%29

Use n to eliminate n in the money and coin count equations.
2q%2Bd%2Bq=20 and 2q%2B2d%2B5q=46
Revise system:
system%28d%2B3q=20%2C2d%2B7q=46%29

Multiply coin counts by 2 as preparation to eliminate d.
system%282d%2B6q=40%2C2d%2B7q=46%29

SUBTRACT:
2d%2B7q-%282d%2B6q%29=46-40
highlight%28q=6%29-----The solution for q quarters.

From that q,
n=2q
n=2%2A6
highlight%28n=12%29------solution for n nickels.

Now using coin count, or by difference, d+12+6=20
highlight%28d=2%29-------solution for d dimes.