Question 489801
The key is that you have as much salt after evaporation as before
In words:
(ounces of salt)/(total salt + water solution at end) = 6%
given:
{{{ .04*32 = 1.28 }}} ounces of salt at start
{{{ 32 - 1.28 = 30.72 }}} ounces of water at start
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Let {{{ w }}} = ounces of water to be evaporated
{{{ 1.28 / (32 - w) = .06 }}}
{{{ 1.28 = .06*(32 - w) }}}
{{{ 1.28 = 1.92 - .06w }}}
{{{ .06w = 1.92 - 1.28 }}}
{{{ .06w = .64 }}}
{{{ w = 10.667 }}}
10.667 ounces of water must be evaporated
check:
That leaves {{{ 30.72 - 10.667 = 20.053 }}} ounces of water
{{{ 1.28 / ( 20.053 + 1.28 ) = 1.28 / 21.333 }}}
{{{ 1.28 / 21.333 = .06000 }}}
OK