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lavre has sixty-one coins, all of whichare dimes and quaters. if the total value of the coins is \$9.85, how many of each kind of coins has she?

If Q = # quarters
and D = # dimes.
Then
Q+D=61
.25Q+.10D=9.85
=================
Two equations and two unknowns. Solve for Q and D. Check my work.

Q = 25
D = 36
It's a system of linear equations so you can put it into a matrix to solve
let Matrix A be a 2x2 matrix
|1 1|
|.25 .1|
and have another matrix, B
|61 |
|9.85|
A^-1 * B will give you the answer

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