SOLUTION: The total value of quarters and dimes in a coin bank is $6.90. If the quarters were dimes and the dimes were quarters, the total value of the coins would be $7.80. a) set up a s

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: The total value of quarters and dimes in a coin bank is $6.90. If the quarters were dimes and the dimes were quarters, the total value of the coins would be $7.80. a) set up a s      Log On


   

Question 1141859: The total value of quarters and dimes in a coin bank is $6.90. If the quarters were dimes and the dimes were quarters, the total value of the coins would be $7.80.
a) set up a system if equations to represent the situation.
b) find the number of quarters in the bank.
please give details, thankyou
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
d dimes
q quarters
0.1d%2B0.25q=6.9

If the dimes and quarters were switched, then 0.25d%2B0.1q=7.80.

More than one way to go but initial system is system%280.1d%2B0.25q=6.9%2C0.25d%2B0.1q=7.8%29

Try adding corresponding members.
0.35d%2B0.35q=14.7
and then dividing by 0.35,
d%2Bq=42
Not a finished solution but only part of a path. (There are fourty-two coins).