Question 687370
Let {{{ n }}} = number of nickels
Let {{{ d }}} = number of dimes
given:
(1) {{{ n + d = 15 }}}
(2) {{{ 5n + 10d = 125 }}} ( in cents )
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(1) {{{ n = 15 - d }}}
and
(2) {{{ 5*( 15 - d ) + 10d = 125 }}} 
(2) {{{ 75 - 5d + 10d = 125 }}}
(2) {{{ 5d = 125 - 75 }}}
(2) {{{ 5d = 50 }}}
(2) {{{ d = 10 }}}
and, since
(1) {{{ n = 15 - d }}}
(1) {{{ n = 15 - 10 }}}
(1) {{{ n = 5 }}}
There are 10 dimes and 5 nickels
check:
(2) {{{ 5n + 10d = 125 }}}
(2) {{{ 5*5 + 10*10 = 125 }}}
(2) {{{ 25 + 100 = 125 }}}
(20 {{{ 125 = 125 }}}
OK