<PRE><B>Question 487943</B>
Let {{{a}}} = number of adult tickets they need to sell
Let {{{s}}} = number of student tickets they need to sell
given:
(1) {{{ a + s = 500 }}}
(2) {{{ 4.5a + 2.5s  = 1650 }}}
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From (2),
(2) {{{ 45a + 25s = 16500 }}}
Multiply both sides of (1) by {{{25}}},
then subtract (1) from (2)
(2) {{{ 45a + 25s  = 16500 }}}
(1) {{{ -25a - 25s = -12500 }}}
{{{ 20a = 4000 }}}
{{{ a = 200 }}}
and, since
(1) {{{ a + s = 500 }}}
(1) {{{ s = 300 }}}
They need to sell 200 adult tickets and
300 student tickets</PRE>