Question 1034089
Let {{{ x }}} = number of adult tickets sold
{{{ 126 - x }}} = number of children's tickets sold
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{{{ 3x + 2.25*( 126 - x ) = 343.5 }}}
{{{ 3x + 283.5 - 2.25x  = 343.5 }}}
{{{ .75x = 60 }}}
{{{ x = 80 }}}
and
{{{ 126 - 80 = 46 }}}
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80 adults and 46 children went to the concert
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check:
{{{ 3*80 + 2.25*( 126 - 80 ) = 343.5 }}}
{{{ 240 + 103.5 = 343.5 }}}
{{{ 343.5 = 343.5 }}}
OK