Question 897189
Let {{{ x }}} = number of baseball cards
{{{ 63 - x }}} = number of hockey cards
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{{{ 3x - 4*( 63 - x ) = 126 }}}
{{{ 3x - 252 + 4x = 126 }}}
{{{ 7x = 126 + 252 }}}
{{{ 7x = 378 }}}
{{{ x = 54 }}}
{{{ 63 - x = 9 }}}
He has 54 baseball cards and 9 hockey cards
check:
{{{ 3x - 4*( 63 - x ) = 126 }}}
{{{ 3*54 - 4*9= 126 }}}
{{{ 162 - 36 = 126 }}}
{{{ 126 = 126 }}}
OK