SOLUTION: in my purse i have 15 coins-quaters,dime, and pennies. i have twice as many quaters as dimes. the total amounts of money is $1.29. how many of each coin do i have?

Question 118882: in my purse i have 15 coins-quaters,dime, and pennies. i have twice as many quaters as dimes. the total amounts of money is $1.29. how many of each coin do i have?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
You have q quarters, d dimes, and p pennies. Each quarter is worth 25 cents, so the value of your quarters is 25q. Likewise the value of your dimes is 10d and the value of your pennies is p.

We know that:
1)

2) ($1.29 is 129 cents)

3)

The first thing we can do is substitute 2d for q in each of equations 1 and 2.

4) => and

5) =>

Now, solve equation 4) for p

6)

And substitute this value for p into equation 5)

Combine terms and solve for d

Now we know we have 2 dimes. That means we have quarters. 2 dimes plus 4 quarters is 6 coins. 15 coins minus 6 coins is 9 coins, so we have 9 pennies.

Check:

Answer checks

Hope you aren't hungry for a Big Mac.
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