Question 1017040
Let {{{ x }}} = ml of solution
{{{ 80 - x }}} = ml of water
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{{{ x / ( 80 - x ) = 1/3 }}}
{{{ 3x = 80 - x }}}
{{{ 4x = 80 }}}
{{{ x = 20 }}}
20 ml of solution was used
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check:
{{{ x / ( 80 - x ) = 1/3 }}}
{{{ 20 / ( 80 - 20 ) = 1/3 }}}
{{{ 20/60 = 1/3 }}}
{{{ 1/3 = 1/3 }}}
OK