Question 469347
Let {{{c}}} = number of children's tickets sold
Let {{{a}}} = number of adult tickets sold
given:
(1) {{{ 4c + 8a = 1176 }}}
(2) {{{ c + a = 172 }}}
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Multiply both sides of (2) by {{{ 4 }}}, and
subtract (2) from (1)
(1) {{{ 4c + 8a = 1176 }}}
(2) {{{ -4c - 4a = -688 }}}
{{{ 4a = 488 }}}
{{{ a = 122 }}}
122 adult tickets were sold
check answer:
(2) {{{ c + a = 172 }}}
(2) {{{ c = 172 - a }}}
(2) {{{ c = 172 - 122 }}}
(2) {{{ c = 50 }}}
and
(1) {{{ 4c + 8a = 1176 }}}
(1) {{{ 4*50 + 8*122 = 1176 }}}
(1) {{{ 200 + 976 = 1176 }}}
(1) {{{ 1176 = 1176 }}}
OK