Question 387717
Let {{{n}}} = number of nickels
Let {{{d}}} = number of dimes
given:
(1) {{{5n + 10d = 215}}} (in cents)
(2) {{{10*(2d) + 5*(n + 28) = 600}}}
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There are 2 equations and 2 unknowns, 
so it's solvable
(2) {{{20d + 5n + 140 = 600}}}
(2) {{{5n + 20d = 460}}}
Now subtract (1) from (2)
(2) {{{5n + 20d = 460}}}
(1) {{{-5n - 10d = -215}}}
{{{10d = 245}}}
{{{d = 24.5}}} impossible
In (1), {{{n}}} has to be odd to get {{{215}}}
In (2), {{{n + 28}}} ends up being odd again
and that can't give me {{{600}}}
These numbers are wrong somehow, I think.