Question 906156
Let {{{ n }}} = number of nickels
Let {{{ d }}} = number of dimes
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(1) {{{ n = 6d }}}
(2) {{{ 5*( n + 6 ) + 10*( d + 6 ) = 330 }}} ( in cents )
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Substitute (1) into (2)
(2) {{{ 5*( 6d + 6 ) + 10*( d + 6 ) = 330 }}} 
(2) {{{ 30d + 30 + 10d + 60 = 330 }}}
(2) {{{ 40d = 330 - 90 }}}
(2) {{{ 40d = 240 }}}
(2) {{{ d = 6 }}}
and
(1) {{{ n = 6d }}}
(1) {{{ n = 6*6 }}}
(1) {{{ n = 36 }}}
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She has 36 nickels and 6 dimes
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check:
(2) {{{ 5*( n + 6 ) + 10*( d + 6 ) = 330 }}} 
(2) {{{ 5*( 36 + 6 ) + 10*( 6 + 6 ) = 330 }}} 
(2) {{{ 5*42 + 10*12 = 330 }}}
(2) {{{ 210 + 120 = 330 }}}
(2) {{{ 330 = 330 }}}
OK