Posted by **selena** on Sunday, March 8, 2009 at 10:33pm.

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?

- grade 9 math!!!!!!!!!! please help -
**DrBob222**, Sunday, March 8, 2009 at 10:49pm
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.

- grade 9 math!!!!!!!!!! please help -
**Anonymous**, Monday, March 9, 2009 at 1:33pm
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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