Question 945570
"we have 100 coins, a mixture of nickels and dimes"


so we know that {{{n+d = 100}}} where


n = number of nickels
d = number of dimes


you can solve for either variable. I'm going to solve for d: {{{d = 100-n}}}


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The total value of the coins is $8.20, so we also know


{{{0.05n + 0.10d = 8.20}}}


{{{0.05n + 0.10(100-n) = 8.20}}} Plug in {{{d = 100-n}}}


{{{0.05n + 10 - 0.10n = 8.20}}}


{{{-0.05n + 10 = 8.20}}}


Keep going to solve for n. I'll let you do that. Once you find the value of n, you plug it into {{{d = 100-n}}} to get the value of d.