Respuesta :

Answer:

we have 5 nickels and 7 dimes

Step-by-step explanation:

We have a total of 12 coins; n nickels and d dimes.  So, the nickels and dimes that I own are 12 altogether or:

[tex]n + d =12[/tex]

My second piece of information tells me that the value of my coins equals $0.95  We know that a nickel is worth $0.05 and a dime is worth $0.10:

[tex]0.05n + 0.10d = 0.95[/tex]

So our systems of equations are as follows:

[tex]\left \{ {{n + d =12} \atop {0.05n + 0.10d = 0.95}} \right.[/tex]

we solve for d and remplace in the second equation

[tex]d=12-n[/tex]

[tex]0.05n + 0.10(12-n) = 0.95[/tex]

isolate n an we get:

[tex]0.05n + (12*0.10)-0.10n = 0.95\\[/tex]

[tex]0.25=0.05n[/tex]

[tex]n=5\\[/tex]

and we replace n=5 in the first equation:

[tex] d =12-5=7[/tex]

we have 5 nickels and 7 dimes

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