Question 413444
Let {{{a}}} = number of 2.25 tickets sold
Let {{{b}}} = number of 2.50 tickets sold
given:
(1) {{{a + b = 652}}}
(2) {{{2.25a + 2.5b = 1535.5}}}
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(2) {{{225a + 250b = 153550}}} Multiply through by {{{100}}}
Multiply both sides of (1) by 225 
and subtract (1) from (2)
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(2) {{{225a + 250b = 153550}}}
(1) {{{-225a - 225b = 146700}}}
{{{25b = 6850}}}
{{{b = 274}}}
and, since
(1) {{{a + b = 652}}}
(1) {{{a + 274 = 652}}}
{{{a = 652 - 274}}}
{{{a = 378}}}
378 of the 2.25 tickets were sold
274 of the 2.50 tickets were sold
check the answer:
(2) {{{2.25*378 + 2.5*274 = 1535.5}}}
{{{850.5 + 685 = 1535.5}}}
{{{1535.5 = 1535.5}}}
OK