Question 1124812
Let {{{ x }}} = pounds of $7/pound coffee needed
{{{ ( 7x + 4*30 ) / ( x + 30 ) = 5 }}}
{{{ 7x + 120 = 5*( x + 30 ) }}}
{{{ 7x + 120 = 5x + 150 }}}
{{{ 2x = 30 }}}
{{{ x = 15 }}}
15 pounds of $7/pound coffee needed
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Check:
{{{ ( 7*15 + 120 ) / ( 15 + 30 ) = ( 105 + 120 ) /  45 }}}
{{{ 225/45 = 5 }}}
OK