Answer :

iGreen
Make a system of equations.

[tex]\sf0.10d+0.25q=6[/tex]
[tex]\sf~q = 2d[/tex]

Plug in 2d for 'q' in the first equation:

[tex]\sf0.10d+0.25q=6[/tex]

[tex]\sf0.10d+0.25(2d)=6[/tex]

Multiply:

[tex]\sf0.10d+0.50d=6[/tex]

Combine like terms:

[tex]\sf0.60d=6[/tex]

Divide 0.60 to both sides:

[tex]\sf~d=10[/tex]

Now plug this into any of the two equations to find 'q':

[tex]\sf~q = 2d[/tex]

[tex]\sf~q = 2(10)[/tex]

[tex]\sf~q = 20[/tex]

So she has 10 dimes and 20 quarters.
siahsavage
.10x = dimes  ----------\
                               + 6.00
2(.25x) = quarters---/


.10x + 2(.25x) =6.00                 .10(10) + 2(.25(10)) =6.00
10x + 50x = 600                              1 + 2(2.50) = 6.00
60x = 600                                          1+ 5.00 = 6.00
x = 10                                                    6.00 = 6.00

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