Question 424034
Let {{{d}}} = number of dimes
Let {{{n}}} = number of nickels
given:
(1) {{{d + n = 150}}}
(2) {{{d = n + 12}}}
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Substitute (2) into (1)
(1) {{{ n + 12 + n = 150}}}
(1) {{{ 2n = 150 - 12 }}}
(1) {{{ 2n = 138}}}
{{{n = 69}}}
and, since
(2) {{{d = n + 12}}}
{{{d = 69 + 12}}}
{{{d = 81}}}
He has 81 dimes and 69 nickels