Question 458515
let {{{ n }}} = number of nickels
Let {{{ q }}} = number of quarters
given:
(1) {{{ n = 4q }}}
(2) {{{ 5n + 25q = 180 }}}  ( in cents )
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(1) {{{ q = n/4 }}}
Substitute this in (2)
(2) {{{5n + 25*(n/4) = 180 }}}
Multiply both sides by {{{4}}}
(2) {{{ 20n + 25n = 720 }}}
(2) {{{ 45n = 720 }}}
(2) {{{ n = 16 }}}
There are 16 nickels
check:
{{{ q = n/4 }}}
{{{ q = 4 }}}
and
(2) {{{ 5n + 25q = 180 }}}
(2) {{{ 5*16 + 25*4 = 180 }}}
(2) {{{ 80 + 100 = 180 }}}
OK