Answer:
we have 5 nickels and 7 dimes
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:
![n + d =12](https://img.qammunity.org/2020/formulas/mathematics/high-school/dat1yj5vf4z9ar6enpkkc3cxaj1y8apesq.png)
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:
![0.05n + 0.10d = 0.95](https://img.qammunity.org/2020/formulas/mathematics/high-school/j53xwikf8bp32r1re4jr2jocq4n9u31e74.png)
So our systems of equations are as follows:
![\left \{ {{n + d =12} \atop {0.05n + 0.10d = 0.95}} \right.](https://img.qammunity.org/2020/formulas/mathematics/high-school/hfgs9cdsi3rkm1lyjkavzgli18ldj77nyz.png)
we solve for d and remplace in the second equation
![d=12-n](https://img.qammunity.org/2020/formulas/mathematics/high-school/j584r3v5h0xzh8bz4ingdohn6p9m9m0yzm.png)
![0.05n + 0.10(12-n) = 0.95](https://img.qammunity.org/2020/formulas/mathematics/high-school/2496kbxoorkv1shoy5mlvx6q9y8sa7f09v.png)
isolate n an we get:
![0.05n + (12*0.10)-0.10n = 0.95\\](https://img.qammunity.org/2020/formulas/mathematics/high-school/gjwr8uy6l2s8bfz0jqjaqd228zzqkn17q8.png)
![0.25=0.05n](https://img.qammunity.org/2020/formulas/mathematics/high-school/sdw27jjrutklox35hvgthbi2e8z0hs4psy.png)
![n=5\\](https://img.qammunity.org/2020/formulas/mathematics/high-school/2w21h5jn1rs0ua7pcjpxmrnibbjo03wa77.png)
and we replace n=5 in the first equation:
![d =12-5=7](https://img.qammunity.org/2020/formulas/mathematics/high-school/n9u8a4g8wj80rpu97m93x2zryzpvsy72dk.png)
we have 5 nickels and 7 dimes