Question 707474
Let {{{ w }}} = grams of water to be evaporated
{{{ .4*10 = 4 }}} grams of salt in solution
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In words:
( grams of salt ) / ( grams of original solution minus water evaporated ) = 50%
{{{ 4 / ( 10 - w ) = .5 }}}
{{{ 4 = .5*( 10 - w ) }}}
{{{ 4 = 5 - .5w }}}
{{{ .5w = 1 }}}
{{{ w = 2 }}}
2 grams of water must be evaporated
check:
{{{ 4 / ( 10 - w ) = .5 }}}
{{{ 4 / ( 10 - 2 ) = .5 }}}
{{{ 4/8 = .5 }}}
{{{ .5 = .5 }}}
OK